Temizu. This photo was taken of a hand washing basin in Japan, the basins are used to perform Temizu. When visiting shrines in Japan you should rinse your hands and mouth from the water of the purification fountain before entering. The water is meant to cleanse and remove impurity.
You should first wash your left hand, then your right and then rinse your mouth. Tipping back the ladle washes the ladle handle (as the person in the photo is doing) and you should finish by placing it back face down on the rack.