This is a very rare and desirable genuine rear light up garnish, which is an awesome factory option for R33. This particular item is even rarer than usual as it has chrome lettering instead of normal white, it was removed from a S2 R33 GTR in working condition.
This will need a resistor pack / voltage converter for it to light up. (Can order them online for under $10) Any autoelec will be able to get it working.
Glows green / yellow from factory, but you could pull it apart to convert to LED. Very rare piece of kit.