In Spanish why are the two words bueno and bien mean both good when do you use bien and when bueno What is the difference?

bien actually means "well," such as how bien hecho means well done. In English grammar, sometimes you can use "good" in a sentence, and sometimes "well" can be used. The same goes for Spanish, only that it gets more complicated that, as you have to take into consideration other variations of bueno that might be gramatically correct, such as buen and buena.

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I've read that 'bien' is an adverb and that 'bueno' is an adjective.