This little applet shows a preview of the desktops and lets you also choose by a click with the left mouse button which desktop you want to use.
There is also a very useful context menu:
This option lets the mini pager appear as a tiny preview of the desktops with symbolic rectangles for the running applications.
If this option is chosen, the pager will show the numbers of the desktops
This will let the pager show the names of the desktops, which can be set in the preferences or from Control Center.
If this option is checked, a small button will be shown which shows a bigger preview of the running desktops.
Here you can set the number of desktops you want to have and the names of them.