When we used adverbs in sentences which describe verbs, we often times add an "LY" , to an adjective to make it an adverb. For example, take a look at sentence "The quick brown fox jumps over the lazy dog." In this case, we have the word "quick" which is functioning as an adjective because it is describing the "fox" adjectives describes nouns and so we don't need to add an "LY" to the end of this word because it's working as an adjective in the sentence but they are times that we do need to add an "LY."
Take a look at this sentence. "The fox jumped quickly." In this case the word quick is being used to describe how the fox jumped and so it's an adverb, it's describing a verb and we add "LY" to the end of the word "quick" to make it an adverb. One thing to know is that some adverbs don't work this way for example if we say.
"The fox ran fast." In this case the word "fast" is an adverb, it's describing the way that the fox ran but we don;t add an "LY" to it so often times in grammar there are exemptions to the rule, which is why if your unshared it's good to look it up but it's a general rule of thumb, it's good to add "LY" to an adjective to turn it in to adverb.