The document compares and contrasts count nouns and mass nouns. Count nouns can be pluralized and take indefinite articles like "a" and "an", while mass nouns cannot be pluralized and do not take indefinite articles. Examples are provided of count nouns being used in singular and plural forms as well as mass nouns being used without pluralization or articles. The document also discusses using countable quantities like "a cup of tea" with mass nouns.