What does Joshua 15:63 mean?

But the people of Judah couldn't drive out the Jebusites who lived in Jerusalem, so the Jebusites have lived there with the people of Judah ever since. Joshua 15:63 - Modern Text Bible

(Even though Judah was given Jerusalem, they couldn't take it from the Jebusites. This shows that the conquest wasn't complete and that some original inhabitants stayed.)