Stars are massive celestial bodies and are very far away from each other. The commonly used units for measurement of distance (such as meters, kilometers, miles, etc.) are very inconvenient for measuring and reporting such large distances. Scientists use units such as light years and parsecs for measuring the distance between stars.
1 light year is the distance light will travel in 1 year (in a vacuum).
1 light year = `9.46 xx 10^(15) m = 9.46 xx 10^(12) km`
Parsec is another unit of distance measurement and is equal to 3.26 light years.
1 Parsec = 3.26 light years = `3.09 xx 10^(16) m = 3.09 xx 10^(13) km`
The nearest star to Earth (other than the Sun) is Proxima Centauri which is 4.2 light years away from Earth.
Hope this helps.