How to distinguish countable nouns from uncountable nouns in sentences

How to distinguish countable nouns from uncountable nouns in sentences

First of all, we need to see if there are any numeral in front of the noun. When it is greater than 1, the countable noun will add s
But when uncountable nouns indicate quantity, they usually use quantifiers, such as a bottle of water
There are also some special singular and plural homographs, such as people