I'm no expert but it looks like a prolapsed vent? I found an article below which has home treatment. There may be additional information or advice on another forum here on the website if you search?
Treatment: If you see portions of your hen’s cloaca protruding through her vent, please be sure to separate her, as she may be a target of pecking/cannibalization. Withhold feed--at least temporarily. While this sounds cruel, withholding feed for a day or two can cause a break in laying for your hen which can give her stressed vent/reproductive tract a much-needed break. If you do withhold feed, it can be a good idea to provide a vitamin supplement in her water in case the problem is caused or exacerbated by a nutritional deficiency. You can don a latex or non-latex glove, and lubricate with petroleum jelly or an antibiotic ointment (be sure the ointment does not contain painkillers ending in -caine--they are not good for chickens). Use a finger to gently push the protrusion back inside the vent. Preparation H can help a small prolapse. If the prolapse has been pecked or “picked out,” it’s best to consult a vet. Do not treat the pain from a picked vent with an aspirin solution, either: that can thin the blood and cause additional bleeding. Consult a vet if you think your hen needs treatment for pain.