Here "face" represents Yahweh in all of his being. David is confident he will see Yahweh. AT: "because I act in the right way, I will be with you one day" (See: [[rc://en/ta/man/translate/figs-synecdoche]])
David believes that after he dies, he will be with Yahweh. This can be made clear in the translation. AT: "After I die, I will be happy to wake up in your presence" (See: [[rc://en/ta/man/translate/figs-explicit]])