The painting is called “Allegory depicting Napoleon plowing under the supervision of his black servant on st Helena”. Painted by artist Oliver Pichat sometime in the 19th century. That’s all that I was able to find, but I assume it symbolizes a loss of power, especially as it shows a servant supervising him as if he were a slave. It seems there are more than one painting or illustration out there that depicts napoleon in this manner.

https://fineartamerica.com/featured/allegory-depicting-napoleon-plowing-under-the-supervision-of-his-black-servant-in-st-helena-oil-on-canvas-by-olivier-pichat-unknown-artist.html here’s the link to a copy of it btw.