These two phrases mean basically the same thing. Together they emphasize that God punished them immediately, even while they were eating the meat. Alternate translation: "While they were still eating the meat" (See: [[rc://en/ta/man/jit/figs-parallelism]])
This metaphor speaks of Yahweh's anger as if it were a fire that Yahweh was kindling. Alternate translation: "Yahweh became very angry with them" (See: [[rc://en/ta/man/jit/figs-metaphor]])