This is for gesture control! It ditches the navigation on the bottom of your phone and replaces it with gesture control instead, so as opposed to clicking a back button you swipe left or right on the the screen, the home button moves to an IOS-esque bar on the bottom of the screen. It's kinda nifty actually!
As it is a navigation feature I don't believe there's an option to change its' functionality. Other Gestures could possibly be used as an alternative? Like full palm on screen or double press the power button, I don't know if this helps at all but hopefully it clears something up
Download the Good Lock app from Samsung store. Its basically extra functions and options added on Samsung devices the navigation section may have something.