What ceiling/wall lamps fit these ports
What country is this from? I'm guessing Netherlands as Attema is located there.

Looks like it's a simple two wire terminal block and hanger hook. Under magnification, I can see the screw threads protruding into the opening where the wires insert.

You strip the lamp cord back about 1/4". After turning off the power, loosen the screws, slide the conductors in each terminal opening and tighten. 

The lamp hangs from a chain attached to the hook. Allow for slack in the cord so it doesn't pull against the terminal block.