This picture is of Lady MacBeth sleepwalking while her maid and doctor watch her. While she is sleepwalking, they notice she is also washing her hands like there is something there that she can't get rid of, and all the while she is saying, "Out, damned spot! out, I say!--One: two: why, then, 'tis time to do't..." She is full of so much guilt, that it has driven her mad. She speaks in her sleep of killing Banquo, but she never actually kills him. What she feels is the guilt and tyranny she pushed onto Macbeth to make him do these horrible crimes. She, earlier on, had expressed that she wishes to be "unsexed" so she would have the strength to do such a dastardly deed. She realizes though, that she couldn't kill King Duncan because he reminded her of her father while he slept.
The symbol that I believe really is apparent in the scene is purification by water. It is as though it will erase any sin or guilt from the hands that did it. So she continually tries to clean her hands as to hopefully get rid of the thought that keeps forming in her head.
Another symbol is light and dark. While Lady Macbeth was sleepwalking, the maid notices that she would always have a candle with her to keep away the dark. This shows that she was afraid of what might happen if she were to be alone in the dark, knowing what she had caused. Her maid had also said to the doctor that, "She has light by her continually; 'tis her command." She was once drawn into the darkness when she was trying to help Macbeth be king, but once it was done, she had the light to draw it away. She no longer wanted to be in the dark anymore.
