An adverb is a part of speech that is regularly used to modify (limit or describe) a verb, verbal, an adjective, and another adverb, or even the rest of the sentence.
slowly stood: slowly modifies the verb stood
too wide: too modifies the adjective wide
very slowly: very modifies the adverb slowly
Many times the adverb ends in ly. [an adjective can be changed
into an adverb by adding ly: sly - slyly; slow - slowly; quick -
quickly; and so on]
Words commonly used as prepositions can also be used as adverbs.
I walked off of the stage. Off is an adverb in this sentence. Of the stage is a prepositional phrase.