These two phrases have the same meaning and are used together to emphasize the remnant of people who will survive. (See: [[rc://en/ta/man/jit/figs-parallelism]])
This speaks of Yahweh doing something because of his zeal as if his "zeal" were actually doing the action. Alternate translation: "Because of his zeal, Yahweh of hosts will do this" or "Yahweh of hosts will do this because of his zeal" (See: [[rc://en/ta/man/jit/figs-metonymy]])