I will force the nations out of your land and enlarge your borders. Then no one will try to take your property when you come to worship me these three times each year.
As you attack these nations, the LORD will force them out little by little. He won't let you get rid of them all at once--if he did, there wouldn't be enough people living in the land to keep down the number of wild animals.
The Jebusites lived in Jerusalem, and the people of the Judah tribe could not capture the city and get rid of them. That's why Jebusites still live in Jerusalem along with the people of Judah.
Ephraim could not force the Canaanites out of Gezer, so there are still some Canaanites who live there among the Israelites. But now these Canaanites have to work as slaves for the Israelites.