How to interpret art has a helpful article about interpreting art called How to Read a Painting:

Developing a casual understanding of art is not all that difficult. It is true that some people devote their entire lives to studying the minutest details of an artists’ work, but there’s no need to become an expert to have a meaningful relationship with art. All it takes is a moderate attention to detail, a little bit of patience, and a willingness to reflect on your own feelings.

Some art is easier to appreciate than others, some easier to understand. Good art, like good poetry, often has a number of layers that can be appreciated if you take the time to look.