MacOS doesn’t have a taskbar, but it does have something very close: the Dock (Chapter 5). Open programs are indicated by a small dot beneath their icons in the Dock. If you hold down your cursor on one of these icons (or right-click it, or two-finger click it), you get a pop-up list of the open windows in that program, exactly as in Windows.
On the other hand, some conventions never die. Much as in Windows, you cycle through the various open Mac programs by holding down the 
key and pressing Tab repeatedly.