The book of Amos is a record of the messages of the prophet Amos. As with most prophets, Amos’s message focused on current events for the people of Israel (the Northern Kingdom of Israel), but also had a secondary meaning, anticipating the life of Jesus.
Amos was a preacher, or prophet, in Israel; he lived during the reign of King Jehoash (Joash) of Israel. He spoke of a coming doom for Israel and the surrounding nations, of Israel’s disobedience and coming destruction, and of visions of the future.
Amos is sometimes called a minor prophet. This doesn’t mean he wasn’t important, but merely that the book named after him is shorter. (Compare this to the major prophets, whose books are much longer.)