Such a thing allows the use of the iron AND the light at the same time.
The buttons on either side are a switch - pressing the red button turns the switch on, the black button is off.
Only one of the outlets is switched - the one directly in line with the plug. This allows the light to be switched on or off while leaving the side outlet permanently powered.
The whole thing is fixed together with a single screw.
The threaded section on one of the sockets is for a plastic ring used to hold a lampshade in place - this is missing.
As mentioned earlier, the switch only affects the lower outlet, the side socket is permanently connected.