Advanced Options allow you to add extra functionality to your Event Page:
For Group Bookings Collect Buyers Information: Once per order or For each ticket. Default value Once per order means that buyer (attendee) will have to fill contact and billing information only once even if several tickets or registration types are chosen. If you would like to collect contact and billing information for every ticket or registration type, For each ticket option has to be set.
Twitter Hashtag: the hashtag that will be used in a message if you would like to share your Event on Twitter.
Show Country List on the Event Check Out Page: if this option is checked, attendee will have to select country in contact information section.
Allow User to Manage Tickets: if this option is checked, Manage Tickets button will be added to event page that allow attendee to log in and manage his or her tickets (e.g. print confirmation).
Show Customized Message on the Thank You Page: if this option is checked, you can create and customize the message that will be displayed when ticket is bought under order details section on Thank You Page.
Here is a video with more info about the Advanced Options: Advanced Options