Nouns, Adjectives, Adverbs and Verbs are all different word classes which perform their own function in written texts.
Nouns are words used to identify people, objects or places. For instance, "Sam", "table" and "London" are all examples of nouns.
Verbs, also known as 'doing' words identify an action, occurrence or state of being. "Fell", "existed" and "threw" are all verbs.
Adjectives and Adverbs are both modifying word classes, meaning they describe objects or actions. An adjective could be "green", "beautiful" or "round". However, "quickly", "happily" or "sometimes" are examples of adverbs.