Adjective is a describing word, a part of speech, which qualifies a noun or a noun phrase. Simply, adjectives describe nouns, they give more more information about them. Examples of adjectives: good, bad, cheap, round, rectangular, wealthy, poor, red, blue, black, pale, tanned, wooden, metalic, French, Filipino, nice, little, mean, generous, far, etc.
They modify the nouns, for example:
This car is fast. What is the car like? Fast.
Adverbs modify verbs, adjectives or other adverbs, for example:
The baby cries loudly. How does the baby cry? Loudly.
Adverbs answer questions like how? in what way? where? when? They describe manner, level of certainty, frequency, time, place, etc. They often can be formed from adjectives by adding the suffix -ly.
Examples: loudly, undoubtedly, quite, very, yesterday, beautifully, quietly, quickly, nicely, tastefully, generously, easily, etc.