Light is an electromagnetic wave. It is the visible part of the electromagnetic spectrum, between infrared and ultraviolet. Light has the same properties as the other electromagnetic waves.
Like all electromagnetic waves, light is a transverse wave and it can travel through a vacuum. It does not need a medium, so light from the Sun and from distant stars reaches us through space. In a vacuum its speed is 300 000 000 m/s, the same as radio waves and gamma rays.
Light transfers energy from a source to an absorber. For example, light from the Sun takes about 8 minutes to reach the Earth and warms whatever absorbs it. Different colours of light have different wavelengths and frequencies, but they all travel at the same speed in a vacuum.