What does Joshua 13:3 mean?

This includes the land from the Shihor River, east of Egypt, up to the border of Ekron in the north. This whole area is considered Canaanite, and it covers the five Philistine rulers: Gaza, Ashdod, Ashkelon, Gath, and Ekron, plus the Avvim to the south. Joshua 13:3 - Modern Text Bible

(This verse details the Philistine territory, naming their five main cities and the Avvim people.)