After reviewing verbs like do/does/did and the verb "to be", this lesson distinguishes between adjectives and adverbs. Adjectives describe or modify nouns and pronouns, such as "big table" or "cute puppy". Adverbs describe or modify verbs, adjectives, other adverbs, or entire sentences, for example "quietly going", "really handsome", or "incredibly slowly". The lesson provides examples of how to identify adjectives and adverbs based on their location in sentences and suffixes like -ly to indicate adverbs.