Light travels in space by propagating as electromagnetic waves. These waves consist of electric and magnetic fields that oscillate perpendicular to each other and to the direction of propagation. When light is emitted from a source, such as a star, it travels through space in a straight line until it encounters an obstacle or is affected by gravity.
The reason light can travel such vast distances in space is due to the vacuum nature of space itself. Unlike in a medium such as air or water, where light can be slowed down, space is mostly empty, devoid of particles or molecules that would interact with light and slow it down. Therefore, light can propagate at its maximum speed, known as the speed of light, as it travels through the vacuum of space.
It's important to note that while the speed of light is incredibly fast, it is not instantaneous. Even though light can travel enormous distances, it still takes time for light to reach us from distant stars and galaxies. This means that when we observe objects in space, we are actually seeing them as they appeared in the past, given the time it takes for their light to reach us.