The phrase "my right hand" refers to the place of honor. AT: "Sit at the place of honor which I have for you" (See: [[rc://en/ta/man/translate/figs-idiom]])
Here David describes Yahweh placing his master's enemies under his power and control as putting them under his feet like a footstool. AT: "put your enemies under your power" (See: [[rc://en/ta/man/translate/figs-metaphor]])