Countable Nouns

What is a countable noun?

Countable nouns (also known as count nouns) are nouns that can be considered as individual, separable items, which means that we are able to count them with numbers—we can have one, two, five, 15, 100, and so on. We can also use them with the indefinite articles a and an (which signify a single person or thing) or in their plural forms .
Countable nouns contrast with uncountable nouns (also known as non-count or mass nouns), which cannot be separated and counted as individual units or elements. Uncountable nouns cannot take an indefinite article, nor can they be made plural.
Concrete vs. Abstract Countable Nouns

Both concrete and abstract nouns can be countable. Concrete nouns name people, places, or things that are tangible—they can be seen or touched. Abstract nouns, on the other hand, name intangible things, such as ideas, concepts, feelings, or attributes.
Concrete countable nouns

Concrete nouns are a bit easier to understand as being countable—after all, they are things that we can see and feel, and so we can usually count them. Consider the following, for example:
cup
ambulance
phone
person
eel
computer
doctor
Each of these can be considered as an individual item or unit, which means that we are able to count them:
Singular
Plural
a cup
two cups
an ambulance
several ambulances
a phone
10 phones
a person
many people
an eel
three eels
a computer
a few computers
a doctor
some doctors
Abstract countable nouns

Even though abstract nouns are not tangible, many of them can still be counted as separable units. Like concrete nouns, they can take a or an or can be made plural.
Consider these abstract nouns:
conversation
emergency
reading
aspiration
emotion
belief
Now let’s see how they can be counted:
Singular
Plural
a conversation
two conversations
an emergency
several emergencies
a reading
10 readings
an aspiration
many aspirations
an emotion
hundreds of emotions
a belief
certain beliefs
Grammar with countable nouns

When we use countable nouns, certain elements in a sentence will change depending on whether the noun is singular or plural.
Third-person singular vs. third-person plural pronouns

If a countable noun is being represented by a third-person pronoun, we must take care to use the correct singular or plural form.
Singular

When a noun is singular and names a person (or, sometimes, a pet) whose gender is known,* then we use the third-person singular he, him, or his (masculine) or she, her, or hers (feminine). For example:
“The man left early, so I didn’t get a chance to talk to him.” (Man is singular, so it takes the third-person singular pronoun him.)
“The president has many things that she wants to accomplish in office.” (President is singular, so it takes the third-person singular pronoun she.)
“We taught our dog to know which bed is his.” (Dog is singular, so it takes the third-person singular pronoun his.)
If the noun names a singular place, thing, or non-domestic animal, then we must use the third-person neuter pronoun it:
“I hate this computer because it is so slow!”
“The cow lowed softly as it ate.”
“Some people dislike this town, but I’ve always loved it.”
Plural

When a noun is plural, we use the same third-person pronouns for people, places, animals, and things: they, them, and theirs.* For example:
“The parade floats are spectacular! I love watching them go down the street.”
“Bill and Samantha told me they were coming over later.”
“Make sure the children know which bags are theirs.”
*Usage Note: “Singular they”
English does not have a way of identifying a single person with a pronoun if his or her gender is not known, so sometimes the third-person plural forms (they, them, etc.) are used as a gender-neutral alternative to the third-person feminine/masculine forms. This is sometimes called “singular they.”
For example:
“You shouldn’t judge someone until you know what they are really like.”
“If anyone needs extra help with their studies, they should feel free to see me after class.”
While it is still considered incorrect by some writers and writing guides, especially in American English, “singular they” is gradually becoming accepted as the norm, especially in instances with indefinite pronouns that sound plural but are grammatically singular (like anyone in the example above).
Subject-Verb Agreement

Because countable nouns can be either singular or plural, it is very important to use the correct subject-verb agreement when they are functioning as the subject of a clause.
Subject-verb agreement refers to using certain conjugations of verbs for singular subjects and using other conjugations for plural subjects. This happens most noticeably with the verb to be, which becomes is or was with singular subject nouns and are or were with plural subjects.
For example:
“My brother is back from college.” (singular present simple tense)
“The company was in financial trouble.” (singular past simple tense)
“Many people are getting frustrated with the government.” (plural present simple tense)
“The computers were rather old.” (plural past simple tense)
For any other verb, we only need to make a change if it is in the present simple tense. For most verbs, this is accomplished by adding an “-s” to the end if it is singular and leaving it in its base form if it is plural. For example:
“My father runs his own business.” (singular)
“But his sons run it when he’s away.” (plural)
“The dog wags his tail when he is happy.” (singular)
“Dogs sometimes wag their tails when they’re angry or scared.” (plural)
The verbs have and do also only conjugate for singular subjects in the present simple tense, but they have irregular forms for this: has and does. For example:
“The apple has a mark on it.” (singular)
“All the apples have marks on them.” (plural)
“The teacher does not think it’s a good idea.” (singular)
“The other teachers do not mind, though.” (plural)
Finally, the modal auxiliary verbs will, would, shall, should, can, could, might, and must do not conjugate for singular vs. plural subjects at all—they always remain the same. For instance:
“This phone can also surf the Internet!” (singular)
“Most phones can do that now.” (plural)
“The president will arrive in Malta next week.” (singular)
“The other diplomats will arrive shortly after that.” (plural)
Nouns that are both countable and uncountable

The general idea of countable versus uncountable nouns is simple. If something can be counted with numbers, then it is countable, as the name suggests; if not, then it is uncountable.
However, words in English often carry a number of different meanings, and these can affect whether a word will be considered countable in one instance compared to another.
Take, for instance, the following example featuring the abstract noun love:
“He’s just looking for love.”
This is a clear instance of an uncountable noun. The abstract idea of love cannot be counted with numbers and is thus uncountable. However, the word love can also mean “a person or thing one loves.” When carrying this particular meaning, love is countable. For example:
“I have two loves in my life: my wife and my work.”
Likewise, many things we would normally consider to be countable have meanings that render them uncountable. For instance:
“How many stones did they use to build this wall?” (countable—This refers to individual stones.)
“This tablet is made of stone.” (uncountable—Stone in this sense refers to the material that composes the tablet; substances and materials are uncountable.)
Because the concrete noun stone has a subtly different meaning in these two different sentences, it is considered countable in one and uncountable in the other. Let’s look at some common examples to help reinforce the concept:
“She doesn’t like hearing any criticism.” (uncountable—the act of making a critical comment or judgment)
“I have a couple of criticismsto share.” (countable—individual critical comments or judgments)
“How many chickens does your uncle own?” (countable—individual live chickens)
“I think I’ll have chicken for dinner.” (uncountable—the meat of the chicken as a substance or material)
“We must all strive to avoid sin.” (uncountable—the idea or concept of sin itself)
“The politician has too many sins to count on one hand.” (countable—individual acts or instances of sin)
These are just a few examples of nouns that can be both countable and uncountable, depending on context and specific meaning. There are far, far too many to list every single one here, so you simply have to know which meaning a word carries in a given context and decide whether that meaning makes the noun countable or uncountable.