Here "lips" and "tongue" are metonyms that represent Yahweh speaking. And, Yahweh speaks with so much anger and power that it is spoken of as if his tongue were a fire. Alternate translation: "When he speaks his fury is like a fire that destroys everything" (See: [[rc://en/ta/man/translate/figs-synecdoche]] and [[rc://en/ta/man/translate/figs-simile]])