Anything that's shaded is protected from the direct light of the sun, like a shaded patio or your shaded spot on the sand under a beach umbrella.
This adjective can be used in two ways: first, to describe things that are blocked from the light or heat. That shaded section of your yard is a terrible place to plant sunflowers! In art, shaded areas are those parts of a picture that you color slightly darker, to capture the sense of a shadow. Shaded is from shade, which has a root that means "dark."