It is an electrical box with a doorbell transformer mounted on it (probably 16 volt transformer?). It is a very common setup, usually installed inside a pantry or utility room. Since its mounted on a box with a proper cover, its electrically safe for 120 volt wiring.

Bruce

It is in my coat closet. We found the doorbell outlet elsewhere. Other side of the plate as in inside the wall? Thin wires just hanging as you see in the picture.

So is there a easy way to install power outlet around it if I want to have a light in my coat closet.

Are you using the transformer? If not, then you could simply remove it and put a receptacle or light fixture in the existing box (turn off the power before you look). I would suggest you turn off the power and open up the box and see what's there! And post a photo.

Doorbell transformer?