Every event has a dynamic event page. It can be indexed on Google and search engines as well. When indexed by Google, it is listed in the special Google Events Search and brings new prospective members to the group.
To index group events in Google search, set the Visibility under the Permissions settings to Public.
Alternatively, if the event is Members Only, it is not shown on the group page, not indexed by Google or search engines, and remains private to all members in the group. No one can join the event without being explicitly invited or existing members of the group.