This fake event form is designed to demonstrate the various field types that can be placed on an event and also to show some reusable fields you can insert on your event.
The last tab is designed so you can just exit the form without having to register.
Group pricing allows you to require one of several commerce items to be selected.
It allows you to list two or more commerce items, like say a shirt for $10 and a pair of pants for $50 but you must choose one of them.
I don't show it because of the way it works but the function does exist - contact me if you want to know more about it.