좋은 and 좋아요 both mean ‘good’ however uses are different. A basic form of 좋은 and 좋아요 is 좋다. All of basic form for verb and adjective in Korean ends with -다. When you make a conversation, you should delete -다 and then add some endings such as -아요 or 았어요.

좋은 is 좋다 + 은 which is a modifier. It modifies nouns. For example, 좋은  사람, 좋은 책, 좋은 영화. Therefore 좋은 needs a noun after that, so  좋은이에요 or 좋은 있습니다 are wrong.  So do other verbs and adjectives. You can click here to learn more about -은.

On the other hand, 좋아요 is 좋다 + 아요 which is a present/polite ending. For example, 한국이 좋아요 or 날씨가 좋아요. You can click here to learn more about -아요.