Exposed wiring repair?
I see some exposed copper on the white wire if this is what you are talking about I would suggest shrink tubing, it can be shrunk with a match as most don’t have heat guns, the better types have an adhesive sealant that holds and seals much better than electrical tape, tape tends to slide off and move around more than electrical tape but inside a box a proper tape job with 50% overlap would protect the exposed copper from being hazardous. 

50% over lap is starting the wrap at least an inch prior to the damage after the first wrap the over lap of 50% creates 2 thicknesses of tape , for added thickness a second pass provides 4 thickness.  

I would recommend a quality shrink tubing over tape.