It works like a pump dispenser and grates a small amount of soap into your hand when you pump the handle.

The designer,  Nathalie Stämpfli said:

I designed two dispensers that turn block soap into beautiful little flakes. They offer you a new comfortable sensation when they are falling on your hands and easily dissolve in water.
The first version needs to be attached to the wall. You can easily use it with one hand; while you are pushing the grater, you are capturing the flakes. With its open shape it lets the soap block evolve its fragrances into the room.
The second version is a grater that can stand by itself. Therefore it’s more flexible in usage. It could be placed in the same way as a shower gel or shampoo.

via nathaliestaempfli.com