Joshua is old so God basically tells him there is a lot of land you didn’t conquer. However, what land you did conquer needs to be divided up between all the different tribes of Israel and the rest of this chapter spells that out. The only tribe that doesn’t get land is the tribe of Levi whose inheritance was God himself.
Or to put it another way:
Joshua is old and ill. The campaign for land can’t continue. He doesn’t seem to have an heir, so the land is divided up amongst all the tribes, except for the tribe of Levi which gets bupkis.
Joshua 13:33 “But unto the tribe of Levi Moses gave not any inheritance: the Lord God of Israel was their inheritance, as he said unto them.” Why did Levi get nothing? Seriously – even the half tribe of Manasseh got waterfront property.
You gotta stand up for yourself when spoils of war are being divided, otherwise you will get bupkis.