What does 2 Samuel 8:2 mean?

David also defeated the people of Moab. He made them lie down on the ground and measured them out with a rope. He put two lengths to death and let one length live. The Moabites became his subjects and paid him tribute. 2 Samuel 8:2 - Modern Text Bible

(David deals harshly with Moab, showing both his authority and the seriousness of his rule. The survivors are left to serve him and pay taxes, showing his dominance.)