What does Matthew 12:41 mean?

The people of Nineveh will stand up at the judgment with this generation and condemn it, because they turned back to God when Jonah preached to them. And now someone greater than Jonah is here, but you refuse to listen. Matthew 12:41 - Modern Text Bible

(Jesus says the people of Nineveh, who repented at Jonah's message, will judge those who reject him.)