The document discusses the difference between countable and uncountable nouns. Countable nouns have both a singular and plural form, while uncountable nouns only have one form. With countable nouns, we use "a/an" with the singular and "some/any" with the plural. However, with uncountable nouns we do not use "a/an". Common uncountable nouns include liquids, foods eaten in parts, items used in parts, and general concepts like time, money, and information. The document also explains how to use "how much/how many" with countable versus uncountable nouns.