Here "feet" represents Christ's lordship, authority, and power. Alternate translation: "put all things under Christ's power" or "made all things subject to Christ" (See: [[rc://en/ta/man/jit/figs-metonymy]])
Here "head" refers to the leader or the one who is in charge. Alternate translation: "ruler over all things" (See: [[rc://en/ta/man/jit/figs-metaphor]])