It's a 12v CPU fan. There was a gas detector there before that kept going off because of all the Lysol and hair spray coming from the bathroom.
I replaced it with a larger one that wouldn't fit in the same place, so I relocated it on the panel below the stove. This left a few holes and wires hanging out at the old spot, so I just cut the wire hole bigger(used a 1 3/4" hole saw), screwed the fan on using the old screw holes(got lucky with them lining up), and used the wires that were powering the detector. Also installed a black toggle switch above the fan. After that, I decided it needed to look better, so I attached a small air filter I found at Walmart using Velcro.