The English words good and well are often confused by native and non-native speakers of English – this is a good lesson that will put you well on your way to understanding the difference.
Good is an adjective, which means that it modifies nouns.
Good can be used with copular verbs (that is, verbs which express a state of being, such as to be, to seem, and to appear), but it is still an adjective modifying a noun, not a verb.
Well is an adverb, which means that it modifies verbs, adjectives, and other adverbs.
Well can be used as an adjective to mean "in good health."
The Bottom Line
The confusion between good and well comes from their similar meanings, and a general confusion between adjectives and adverbs. Take a moment to think about what the word is modifying: if it’s a verb, you’d do well to use well; otherwise, the good choice is good.
More English difficulties