Paintings in Elden Ring are Info Items scattered all around The Lands Between that act as a form of treasure hunt. The Wandering Artist Spirit's Paintings depict specific locations you'll have to find in order to meet the spirits of the artists themselves. Upon finding and inspecting one of the seven drawings, a ghost of the artist will manifest at the location from which they were painted, granting a specific reward. Note that the location you must seek is not the structure or landscape depicted itself, but rather the spot the artist would have been when painting it. This page covers a full list of all the Paintings found in Elden Ring, including their location, solution, and rewards.
Elden Ring Paintings Guide