At the top of the panel you can find the Filter bar, and at the bottom there are the buttons that let's you Add or Remove a view.
Inbetween is the list of your Favourite Views which are ordered by View Type and their Name. The views also have an icon that shows their Type. Hovering over a view a tooltip will show up, which contains some additional data about the a view, like their Type, or the applied View Template if there is any.
If you have nothing selected in the Project Browser the Add button will add your currently active view.
If you have selected one or more views in your Project Browser, those will be added to your favourites.
Similarly to addition, any view that is selected in your Favourite Views panel can be removed with the Remove button.
You can also filter your favourites using the Filter bar at the top that uses a simple contains rule.
Just simply double-click any of your Favourite Views to open that view.
The data about your Favourite Views is stored in the actual Revit© ****file, so you need to Save / Synchronize with Central if you want to keep your updates.