Countable nouns are nouns that can be counted and have a plural form. They refer to individual, separate items or units that can be counted as distinct entities. For example, "apple" is a countable noun because you can count individual apples (one apple, two apples, three apples, and so on).
It's important to note that not all nouns are countable. Some nouns, called uncountable or mass nouns, cannot be counted as individual units. Examples of uncountable nouns include "water," "air," and "money."
Understanding countable nouns is important for constructing grammatically correct sentences and using appropriate determiners and quantifiers. Practice identifying countable nouns and using them in sentences to reinforce your understanding of this concept.