The distance of the stars from the Earth and the distance between different stars are very large. It is inconvenient to express these distances in kilometer(km). Hence these large distances are expressed in light years.
One light year is the distance travelled by light in one year.
One light year is equal to 9.46 x 1012 km.
A star is located eight light years away from the Earth. This means that the distance between the star and the Earth is equivalent to the distance travelled by light in eight years, i.e., a star is located 8 x (9.46 x 1012) = 7.6 x 1013 km away from the Earth.