Adjectives are used to describe, or modify, a noun. A noun is an object or thing. But there are a lot of different ways that a noun can be described. For example, if you are talking about an apple, it would be helpful to know some extra details about what it looks like: It could be a big apple, a small apple, a red apple or a green apple.
There are many different types of adjectives, and they can describe several different things. First off: all colors are adjectives. By describing something as "red," you are adding detail, therefore it is an adjective. In that same vein, anything used to describe the way something looks or feels is an adjective. Big, small, fat, skinny, rough, soft --- these are all adjectives.
Adverbs are used to modify a verb. Adverbs usually end in the suffix "-ly." For instance: the cat ran quickly. By adding a descriptive word to a verb, you are detailing not only what the subject is doing, but how they are doing it. The more vividly you describe something the better your audience will understand your meaning.
Adverbs can be used to describe any sort of action, but they can also be used to modify an adjective. Adverbs like "really," "very" and "wonderfully" can all be used to further describe a noun. For instance: "that rock is very hard." It would be enough to say that the rock is hard, but by adding the adverb "very," you are emphasizing just how hard the rock actually is.