The angel of Yahweh asks this rhetorical question to emphasize the positive answer that it anticipates. This can be translated as a statement. AT: "Joshua is a brand pulled from the fire." (See: [[rc://en/ta/man/translate/figs-rquestion]])
A brand is a burning piece of wood. The angel of Yahweh speaks of Joshua being rescued from captivity in Babylon as if he were a piece of wood that someone pulls from a fire before the wood is completely burned. (See: [[rc://en/ta/man/translate/figs-metaphor]])