What does Numbers 18:23 mean?

It's the Levites' job to take care of the tent and everything that happens there. If anyone else tries to do their work, they'll be punished. This is a permanent rule for all your generations. The Levites won't get any land among the other Israelites. Numbers 18:23 - Modern Text Bible

(Levites are set apart for this work, and their role is exclusive. They don't get land like the other tribes; their inheritance is their service.)