Light is subject to a quantum theory called wave-particle duality. This theory proposes that matter exhibits both properties of a particle and properties of a wave.
The experiment that shows light's wave-like properties is the double slit experiment. when light was shone through two slits close together, and a screen was placed behind the slits, the impact pattern didn't look the way one would expect a particle impact pattern to look like. After going though the slits, the light diffracted, creating a wave diffraction pattern on the screen, showing light's wave-like properties.
Light's particle properties are shown in another experiment. Light is passed through "absorber" planes, which don't affect waves. however, when the light passed through the absorbers, the wave after going through the absorber was considerably weaker. This confirmed that light has some particle like properties.
Light is neither particle nor wave and yet exhibits properties of both, which can be experimentally observed.