So if my iPhone display genuine apple part does it means that my iPhone is okay and nothing will happen to it or something ..?

“Grade A+” has absolutely no meaning.

It is a used phone that was apparently refurbished by an unauthorized party using non-Apple parts.

That phone is unsupportable.

Return it if you can and go buy a phone from an authorized retailer.

Update, now that you’ve posted the screen shot, it appears that the display was actually replaced by an authorized service provider with a genuine part…

That’s all it means.

Still, If it was opened up at any time by an unauthorized party, it will be unsupportable.

You buy used, you take your chances…

There is no way anyone can answer that since it’s a used phone, we have no idea what the history of the phone is, and we are not psychic. if you’re worried about it, return it and get your money back and go buy a phone from an authorized retailer.

Your phone will never display "genuine Apple part." It will only display a message if the phone has a part that is NOT a genuine Apple part. This applies primarily to the battery, screen and camera.

And if the part in question is good quality, it doesn’t matter that much; the warning is there primarily so if you sell the phone they buyer knows that a part has been replaced.

That means the display was replaced by someone other than Apple or an authorized service provider.

If anything ever happens, Apple will not service, repair, or support that phone.

Is the listing saying genuine apple part? Because the iPhone will never say that, only if it is a non-genuine part as stated above

I’ll ask again: What are the first 2 characters of the model number?

And it says the warranty coverage has expired, which means the phone was first sold over at least year ago (as the warranty is 1 year)

Are you sure that’s what it says? Can you post a screen shot?

And what is a “grade A” iPhone 12? That isn’t an Apple label.

What are the first 2 characters of your model number?