Adjectives
We use adjectives before nouns and after some verbs, especially be :

Tom is a careful driver.We didn't go out because of the heavy rain.I was disappointed that my exam results were so bad. We also use adjectives after the verbs look/feel/sound etc.

Why do you always look so serious?

AdverbsAn adverb tells us how somebody does something or how something happens:

Tom drove carefully along the narrow road.

She speaks English perfectly.   (verb+object+adverb)

Many adverbs are made from an adjective+ -ly
quick__quickly

We also use adverbs before adjectives  and other adverbs.

It's reasonably cheap restaurant and the food is extremely good