I suppose anselm gave the closest answer ..... it's a cable (power cord) blocker (for avoid to rip off the cable from the device) ..... the small hole is for fit it inside the device with a screw or a hook, and the slots are for pass the cable inside "S" shaped, like this:
You usually find them in cheap devices, cause "professional" ones tend to use different (and more "elegant" ) ones, for justify the higher prices
Damn ..... the funniest thing is that i already have seen something similar, but i'm unable to recall where ..... cover terminals for brake cables for bikes ? ..... naah, too easy .....