Adverbs are basically adjectives that modify verbs, adjectives, or other adverbs but not nouns.  We use them to describe, for example, how fast someone is running, how well someone is driving, how strong the wind is blowing, etc.

Take a look at some usage examples:

    "Jenny is like a rocket.  She runs so quickly!" - "quickly" is describing the verb "runs"
    "The glass broke loudly as it hit the kitchen floor." - "loudly" describes the verb "broke"
    "The little girl carefully examined the young bird's broken wing." -"carefully" describes the verb "examined"

Many adverbs end in -ly, but not all.  Words such as curly, lovely, cuddly, ugly, badly, chilly, etc. are adjectives, not adverbs.  The main way to see if a word is an adverb is to see what it describes.

    lovely girl = "lovely" is an adjective because it describes a the noun "girl"
    walking slowly = "slowly" is an adverb because it describes the verb "walking"
    terribly cold = "terribly" is an adverb because it describes the adjective "cold"