Looks a bit surgical, doesn't it.
It's a combination of one of those crappy solder sucker things and a cheap soldering iron. The bit has a hole in it and the idea is to prime the suction pump, heat up the workpiece with the iron, then press the yellow button, sucking and loose solder through the hole in the bit.
Takes an age to heat up and smells of burning plastic. But for £4.95, it does an admirable job of removing solder. Short of a continuous vacuum desoldering iron (£60+) there's nothing better that I've found.