As far as security goes, it depends on what type of questions you answered.
Otherwise, it's just an incredibly obnoxious ad that seems to be everywhere. I'm somewhat surprised the people run operate ad servers continue to allow this thing to be in their rotation. Well, not that hard to understand. They get lots of money to feed it far more often than other ads.
To remove it, you'll have to clear the browser. Tap the home button twice to call up the application switcher. Slide Safari up and off the screen to close it. Open Settings > Safari. Tap Clear History and Website Data. It will be gone until you visit another site throwing out the same ad.
The best current way to avoid this type of junk is to install an ad blocker. There are a handful of good, free ones available in the App Store. I use the free version of AdGuard on all of my Apple devices. In iOS, make sure to turn it on after installing. This step goes for any ad blocker you install. None of them are on without your say so. Once you have an ad blocker installed, go to Settings > Safari > Content Blockers. Turn the app on.