This stela portrays Chaan Maun preparing for a ritual bloodletting ceremony done to communicate with deceased ancestors. He is assisted by his mother [on the right] and his wife, the sister of Shield Jaguar of Yaxchilan. His mother is handing him a sting-ray spine and a bowl of paper strips.
Note that the eyes of all three protagoists had been defaced, probably in ancient times. This was done in order to ritually kill the power of the stela.