Here "his holy name" represents Yahweh. Alternate translation: "Boast in who Yahweh is" or "Boast in Yahweh" (See: [[rc://en/ta/man/translate/figs-metonymy]])
Here "the heart" represents the person who seeks Yahweh. Alternate translation: "let the people who seek Yahweh rejoice" (See: [[rc://en/ta/man/translate/figs-synecdoche]])