An adverb is a word that modifies anything other than a noun, usually a verb. If you listen patiently to my grammar lesson, you will learn that patiently is an adverb in this sentence.
Many adverbs end in –ly, like quickly, happily, or grudgingly. Sometimes adverbs are harder to spot. If I ask you to talk very loudly, then very is the adverb: it describes how you are supposed to talk.