This is Yahweh's response to David's cry for help from his enemies. David uses the imagery of the earth shaking and fire coming from Yahweh to emphasize Yahweh's terrible anger. (See: [[rc://en/ta/man/translate/figs-metaphor]])
Here Yahweh's anger is compared to fire, which causes coals to ignite and burn. AT: "The flame from his mouth set coals on fire" or "He also sent burning coals from his mouth" (See: [[rc://en/ta/man/translate/figs-metaphor]])