An adverb is a word that accompanies the verb to modify or complement its meaning. You can also modify adjectives, names or other adverbs The position in the sentence will depend on the type of adverb.
My dad speaks quickly.
(Mi papá habla rápido.)
In this example, "quickly" is an adverb that modifies the verb "to speak" to express how it is spoken. Thus it is defined that the father (Subject) speaks (Verb or Action) in a "fast" way (Adverb of Mode).
There are several types of adverbs, we will analyze in this chapter some.