What does 2 Kings 23:17 mean?

Then he asked, 'What’s that monument I see?' The people of the city said, 'It’s the tomb of the man of God who came from Judah and predicted what you’ve just done to the altar at Bethel.' 2 Kings 23:17 - Modern Text Bible

(Josiah notices a grave and learns it belongs to the prophet who had predicted these very events.)