Here "name" represents Yahweh's authority. Alternate translation: "on your behalf" or "by your authority" (See: [[rc://en/ta/man/translate/figs-metonymy]])
Since the army of Judah is fighting in Yahweh's name, Asa speaks of Zerah defeating Judah as if Zerah were to defeat Yahweh himself. Alternate translation: "do not let man defeat your people" (See: [[rc://en/ta/man/translate/figs-explicit]])