What does Joshua 15:1 mean?

This is the land that was given to the tribe of Judah, divided up by their families. Their territory started at the southern border, near the edge of Edom, all the way down to the wilderness of Zin in the far south. Joshua 15:1 - Modern Text Bible

(The passage now lists the boundaries of Judah’s land, starting from the southernmost point near Edom and the desert.)