When we talk about objects, food, drinks, etc. there is something we should consider: Is it countable or uncountable? But... What is "countable"?
COUNTABLE is a noun that we can count: Three dogs, eighty books, seven dwarves... "dogs", "books" and "dwarves" are countable nouns.
UNCOUNTABLE is a noun that we cannot count. "Seven money", "four water" are terrible mistakes😱 (we cannot count 'moneys' or 'waters'). We can, however, say "seven euros" or "four water bottles". By using more nouns we can turn an uncountable noun into a countable one.
We don't use these nouns in an isolated way. We usually need to use A/AN, SOME and ANY but... do you know when to use them appropriately?