This is a very cool Price Brothers brass illuminated Coca Cola clock.  We think this is from the 1950s based on the plug in and the style of the clock.  When you plug it in, the clock works, and there is button on the back so the back lighting can be turned on or off.  
 
Measurements:
19.5 inches wide
8.5 inches tall
4.5 inches deep
 
Otherwise, we love that the glass is painted.  The clock does function, as does the lighting.  The brass shows its age and you can see some discoloration.  There are two hangers on the back if you wanted to hang it.  It is fairly heavy, probably 10-15 lbs.  
 
There is a crack in the bottom glass (pictured) where it says 'Please pay when served'.  We considered replacing this piece of glass, but it is original to the piece, so we left it.  If you want us to replace it after purchase, get in touch and we can make some suggestions and arrangements and get you a price quote for that.