The App Library is a new feature in iOS 14.
You can access on your iPhone by swiping to the right after the last app screen. It is Apple’s way of organizing and categorizing apps to reveal more obscure ones that may be hidden in folders, making them easier to find. You can launch any large-icon apps with a single tap or reveal an entire category of apps by tapping on a four-icon square. With the App Library, almost everything is immediately visible, letting you access all the apps on your phone from this page without having to swipe through all your app pages. In fact, App Library eliminates the need for multiple pages of apps. You can remove entire app pages to rely mostly or solely on the App Library.