The page allows you to copy quotas on all filesystems for some user to one or more other users. There are three ways of choosing which users to copy to :

All Users
  Quotas will be copied to every other user on your system.
Selected Users
  Quotas will be copied to the user or users selected.
Members of Selected Groups
  Quotas will be copied to all users who have one of the selected groups as their primary or a secondary group.