Why is that figure nude?
Well, you may have read this on the label already, but this is actually a biblical scene: Jacob wrestling with an angel. Angels are sometimes depicted without clothes, but I could see why you would see the artist's choice to show Jacob without clothing as interesting. Redon is known for his symbolist paintings, so the nudity may have a specific meaning for him--a return to nature, perhaps? An epic wrestling match where everything is exposed? There could be many reasons behind the nudity that are meaningful for the symbolists.
Who is depicted here?
This early-20th century French work depicts the Biblical figure Jacob wrestling with an angel. Odilon Redon was known for his symbolist works in oils, prints, and pastels.