Two weeks ago i had these light brown spots on the back of my legs but not on my thighs in the sun the spots turn more noticeable what r they?

Skin discoloration: They could be hypopigmented areas, which means a lack of melanin or possibly a fungal infection. Neither are serious conditions. You may want to try an antifungal cream like clotrimazole twice daily for a week. If no resolutions, get an evaluation. Be sure to wear sunblock SPF 30 or greater when outdoors. Avoid sunbathing and reapply sunblock frequently.