What does 1 Kings 12:33 mean?

He went up to the altar in Bethel on the fifteenth day of the eighth month, the month he chose himself, and offered sacrifices. He set up the altar and made priests for the shrines he had made. 1 Kings 12:33 - Modern Text Bible

(Jeroboam personally leads this new worship, showing how far he’s gone in creating his own religion.)