When this feature is enabled, you can always swipe from the bottom up or drag the mouse to the bottom of the screen to open it back.
The first new option is 'Automatically hide the taskbar in tablet mode', which is a new feature included in the new version that let you take full advantage of the screen real estate by removing the taskbar when running apps. Microsoft is not only moving the options to the Settings app, but it's also adding a few new more.
