The book of Zephaniah is a record of the messages of the prophet Zephaniah. As with most prophets, Zephaniah’s message focuses on current events for the people of Israel, but also has a secondary meaning, anticipating the life of Jesus.
Zephaniah focuses the attention of his critical remarks on the political and religious leaders of the nation. Zephaniah, more so than any other prophet, strongly and powerfully communicates that God will decisively deal with evil people (judgment) and that the righteous people will be rewarded (salvation).
Zephaniah 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.)