The closest star to the Earth is the Sun which is at a mean distance of 149.6 million kilometers from the Earth. Mars is not a star but another planet that orbits the Sun like the Earth does. The distance of the Earth from the sun changes around the year as the Earth's orbit is not circular but elliptical in nature.
The time taken by light emitted by the Sun to reach the Earth is approximately 8 minutes and 19 seconds. After the Sun, the nearest star to the Earth is Proxima Centauri which is at a distance of 4.2 light years or approximately 39.9 trillion kilometers from the Earth.