Split view is a Safari feature that let's you have two browser windows open side by side. If you have an iPad mini it might not be so useful but on the 12.9 inch iPad Pro two Safari windows side by side can be very handy.
Tap and hold on any link in Safari, then choose Open in Split View in the pop-up. When you are done you close split view by tapping the X in the top left corner of the right browser half.
Best regards, Niklas 🎈