What does Deuteronomy 4:44 mean?

Then Moses set apart three cities beyond the Jordan toward the sunrise;

that the man slayer might flee there, who kills his neighbor unawares, and didn’t hate him in time past; and that fleeing to one of these cities he might live:

Bezer in the wilderness, in the plain country, for the Reubenites; and Ramoth in Gilead, for the Gadites; and Golan in Bashan, for the Manassites.

These are the testimonies, and the statutes, and the ordinances, which Moses spoke to the children of Israel, when they came out of Egypt,

beyond the Jordan, in the valley over against Beth Peor, in the land of Sihon king of the Amorites, who lived at Heshbon, whom Moses and the children of Israel struck, when they came out of Egypt.

They took his land in possession, and the land of Og king of Bashan, the two kings of the Amorites, who were beyond the Jordan toward the sunrise;