When light strikes a mirror it bounces off. This is called reflection of light. When you see the image of your face in a mirror, you are seeing the reflection of light from your face.
Light reflects from a mirror at the same angle as it arrives.
Below you can see waves of light reflecting off a mirror. You can think of light as being a kind of wave, similar to the waves in the ocean. The distance between the top of one wave and the top of the next wave is called a wavelength. Different colors have different size wavelengths. Violet has the shortest wavelength.