OK, that is definitely a Raspberry Pi. It appears to be connected with an Ethernet cable (yellow) and what I believe is USB cable attached (red cable). It is also powered on which is indicated by the lights on the unit. Is that the power cord coming from the wall? I can only assume it is, and the fact that it just ports into the wall and not an official device or junction box is a little strange. What are the yellow and red cables connected to? Do you live alone and how long have you lived in the house? My first guess is that the Pi was setup for media use, but that is just a guess. Are there any other boxes or connections nearby? My guess is that maybe there was a media setup in that room at one point, but that is assuming you are new to the residence and is something left by an earlier tenant. Of course, this is all speculation. Bottom line, it is a Raspberry Pi, but as to its purpose, I can only guess. I would recommend tracing the yellow and red cables and let us know what you find, and that should help us understand better what you have there.