My doc saw on my MRI that I have arthritis in my back (l14 and l15). Can this arthritis cause leg pains?

Definitely. If the arthritic changes compress a spinal nerve root, they can cause pain in the areas supplied by that root. L4 and l5, in particular, are responsible for sensation down a significant portion of the legs. Depending on the nature of the compression, physical therapy or medication to reduce nerve activity can be helpful with these symptoms.