The menu type “panel sub navigation” is a special one, because it will not be displayed as a top navigation menu entry, but as a entry under “Apps”. Here you can see a panel sub navigation menu entry named “Project Navigation”:
The entry will open as pop-up and contains a project list, which currently is the only supported menu type. The idea is to use the panel sub navigation menu type to create a more comfortable project navigation, but more use cases and menu types are planned in the future.
