There is a problem with your iPhone

Hey everyone i got this phone on ebay it have this error showing "there is a problem with your iphone"

I researched on the internet there are many questions but no answer can anyone help me fix this issue can anyone from apple reply to this issue and if there's any way to fix this or not please reply regarding this

I saw many threads left as is without getting a correct answer

So please reply to this thread and help many people facing the same issue