They have a singular and a plural form. In singular , use them with the indefinite article a/an and the number one.

Example: I saw an eagle when I went hiking last year.

Use countable nouns for things which we can count.

Only countable nouns can be used in the plural. We can also use them on their own to talk about things in general.

Example: Therre are many different plants in the desert.

We can use a/an on their own to talk about things in general.

Example: I love bread, especially with butter.

Use uncountable nouns for things which only have a singular form. We can't count them, and we can't use a/an or the number one with them.

Use with plural countable nouns and uncontable nouns to talk about quantity.

There are some dangerous animals in the desert.

Use to talk about quantty wath countable plural nouns and uncountable nouns.