This document discusses countable and uncountable nouns. Countable nouns can be pluralized and take quantifiers like "a", "few", and "many". Uncountable nouns refer to mass nouns that cannot be counted, like "juice" or "information". They are usually singular and take quantifiers like "some" or "much". Both countable and uncountable nouns can be used in different grammatical structures depending on whether they are singular or plural.