Its called a tart band. It's main purpose it to make him look even more ridiculous than he does normally.
Actually what I hear it is for is to aid his stepovers, as the white is the same height as the ball, so when doing stepovers its hard to tell the ball from his feet. Of course, you can tell his feet, as footballs don't wear boots.
That's basically tape used to prevent the shin pad slipping down and out of position. If there is some extra protection for the ankle like an anklet, then it holds that in place as well. The tape helps to keep the shin pad at the desired level (height-wise) because the pads can slip down during a game, while the sock takes care of the top of the pad.