Count nouns are the most common kinds of nouns, describing anything with a definite or individual shape. For example, you can identify or touch a cup. It has a definite and individual shape that is different from, say, the table or the knife. However, you can not identify or touch a coffee. Coffee is a noncount noun. And in order to make it individual or definite, it must be contained by something. We'll look at this rule soon. Right now you must understand that most count nouns have a definite or individual shape.
However, there are some count nouns that have no good shape because they are abstract concepts or ideas. Units of measurement and a finite number of abstract ideas can be definite and individual. For example, you could say “an idea" and “five projects." Once again, although these are not things you can touch, they can be definite as well as individual.
Names of persons, animals, and things that are distinct
one friend, three children, three tourists, five pencils
groups or classifications
one family, one religion, three groups
Abstract ideas and concepts
one idea, four projects, five schedules, five reasons, one cause
Although the list is brief, you get the idea. As a general rule, if a noun has a definite and identifiable shape, it is a count noun.