Don't quite understand what you're asking. If it's where the hose threads into the fitting of the RV, there is a washer there with a built in screen that needs to be replaced. They're available at any hardware store. You need the washer with the screen.
https://www.amazon.com/JR-Products-160-85-Polar-Flange/dp/B000BGHSNK/ref=asc_df_B000BGHSNK/?tag=hyprod-20&linkCode=df0&hvadid=312035432333&hvpos=1o1&hvnetw=g&hvrand=16699666095278995659&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1012954&hvtargid=aud-643191255296
la-451022790423&psc=1
https://www.amazon.com/Danco-80070-Washers-Screen-Black/dp/B000KKULR2/ref=asc_df_B000KKULR2/?tag=hyprod-20&linkCode=df0&hvadid=167153227674&hvpos=1o2&hvnetw=g&hvrand=6315005416873835035&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1012954&hvtargid=aud-643191255296
la-274916630309&psc=1
Other than that, you'd have to get to the backside of the wall and see if the water pipe which screws onto the back side of the fitting is leaking. If it is, you'll need to unscrew the nut on the pipe and replace the rubber washer inside the nut.
https://parts.unitedrv.com/products/1-2p-cone-washer?variant=35122977665&_vsrefdom=adwords&gclid=EAIaIQobChMIhJbUirLf4QIVhYbACh3nVQMcEAQYBCABEgK8m_D_BwE