Answer:
It's measured in "light years"
1 Light year is the disatnce light travels in 1 year.
Objects and distances in space have many different measurements. For distances, there is the Astronomical Unit(AU), which is the average distance between the earth and the sun. Also the Parsec(pc), which is the average distance to the nearest star. The Kiloparsec(kpc) is used to measure distances within our galaxy or within other galaxies. The Kiloparsec is approximately 1,000 pc, hence it's name. A Megaparsec(mpc) is used for measuring the distance between other galaxies and cosmology and is equal to 1,000,000 pc. Kilometres is the unit used for planets. For dust grains the unit would be microns, etc 1/1,000,000 of a meter. It is also common to compare objects. If I studied a star I might say it's radius is 5 solar radii, which means it is five times the size of the sun.
The most common term for distance in space is the Parsec