Remember that light is particles and waves. Light is both wave and particle, but never both at the same time. You may wonder what does light wave? Nothing. It travels in a vacuum in a field it creates. A changing magnetic field creates a changing electrical field, which creates a magnetic field, and so on. In addition, when you look at a light beam, you're seeing pure, massless energy. When light travels through space, it has wave properties; when it interacts with matter, it behaves like a particle.
Also, high energy light knocks the electrons out of metal.