The dock gets improvements in iOS 11. Instead of just 6 icons there is room for several. You will also find recently used apps to the right on the dock.
Another new feature is that you can open the dock (swipe up from the bottom) in apps. This is handy since iOS 11 has new drag and drop functionality that lets you drag documents and other things between apps. And you can also use it as a way to switch between apps or open app overlays.