When you open up a new tab in Safari on iOS, you're usually shown your most frequently visited sites. If your mobile browsing is as weird and random as mine, this is usually a hodgepodge of web sites you don't actually visit that often. Thankfully you can turn it off.
The new tab page in iOS is populated by both frequently visited sites and your favourites. Personally, I don't like either of these. You can get rid of favourites by tapping and holding on the icon in Safari, then selecting the delete option. To get rid of your frequently visited, hop into Settings > Safari and disable the "Frequently Visited Sites" toggle. This gives you a sense of privacy back and keeps all those weird and wild mobile searches you're doing from showing up on the new tab page.