How do you get rid of light spots on your body? And what is it called?

You need to be more specific. What do you mean by "light spots"?
Acne scars? Scars? Blesmishes?

It sounds like Tinea versicolor. Tinea versicolor is a common fungal skin infection characterized by lighter or darker spots on the skin. The spots are most often found on the chest or back and prevent the skin from tanning evenly. This condition can be treated with antifungal creams, lotions or dandruff shampoos. It can take a month or two for the color to even out. If the spots don't even out, see a doctor for a proper treatment.

If you are of a dark skinned nature this could also be something called vitiglio, which are white discolorations of the skin which is not related to a fungal infection but is genetic in nature.