Leather wax is a wax or oily compound that is used as a leather finisher. It often is blended with oils and conditioners. When applied to the leather, it helps add moisture and also protects the surface from daily use.
Usually, after applying, the leather wax is buffed out to a shine (matte or gloss depending on the formulation). It leaves a smooth, protective surface over the leather that is resistant to dirt, grim, and water.