How to fix safari in my iphone because of illegal

That seems like one of the usual scam pop-ups, trying to get you to contact the scammers.

I’d first try forcing Safari closed: Close an app on your iPhone or iPod touch - Apple Support. Once the tab is closed, hold your finger on the Safari icon until you get a pop-up and use that pop-up to open a new tab. From that new tab and that new Safari session, you can access your browsing history and can clean out any sketchy URLs, and can also view all open tabs (the overlapped-squares icon in Safari) and can slide the problem tab to the left to remove it in the iPhone Safari tab view.

If that fails… Switch to the Settings app, select Safari, Advanced, and Remove All Website Data.

What message, exactly, is on your phone that you need help with?

~Lyssa