This is an especially nice old EXIT sign, which I believe would once have covered a light box. The front, with cut out letters, is a nicely aged copper color, with one hole at bottom center for a screw, plus several screw holes on the left and right sides. Once could certainly incorporate a light fixture behind it, but I'd probably just hang it straight on the wall as is.
13 3/8" long x 6 3/8" tall x 5/8" deep. Very good condition, with some rusting to the front surface, which I think just make it better, and some white paint on the top side.