Countable nouns refer to items that can be counted, even if the number might be extraordinarily high (like counting all the people in the world, for example). Countable nouns can be used with articles such as a/an and the or quantifiers such as a few and many. Look at the sentence below and pay particular attention to the countable noun:
Cat is singular and countable.
Other examples of countable nouns include house, idea, hand, car, flower, and paper.
Uncountable nouns are nouns that come in a state or quantity that is impossible to count; liquids are uncountable, as are things that act like liquids (sand, air). Abstract ideas like creativity or courage are also uncountable. Uncountable nouns are always considered to be singular, and can stand alone or be used with some, any, a little, and much. See the examples below for reference:
Intelligence is an uncountable noun.
Because homework is an uncountable noun, it should be modified by much or a lot of, not many.
Additional examples of uncountable nouns include water, soil, love, literature, and dust.
Both Countable and Uncountable Nouns
Some nouns can be both countable and uncountable, depending on the context of the sentence. Examples of these versatile nouns include light, hair, room, gear, art, and science. See the examples below:
Here, time is countable (a time).
In this sentence, time is uncountable.
In the first sentence, juice refers to the liquid beverage; thus, it is uncountable. In the second sentence, juice refers to the different varieties of juice (e.g., apple, grape, pineapple, etc.), and therefore, is considered a countable noun.