What does Joshua 13:12 mean?

This was the kingdom of Og in Bashan, who ruled in Ashtaroth and Edrei. He was one of the last of the Rephaim. Moses had defeated them and taken their land. Joshua 13:12 - Modern Text Bible

(Og was a legendary king, one of the last of the giants (Rephaim), and Moses had already conquered his territory before Joshua’s campaigns.)