The administer Admins section is where you create and set options for your Forum Admins. You can manage global Admin options, create new Simple:Press admins and set their options. This is also where all Simple:Press admins can manage their personal Simple:Press admin options for display and other personal preferences.
In Simple:Press , an Simple:Press Admin does not have to be a WordPress admin. Forum Admin Explained entry describes in detail the differences between WordPress and Simple:Press administrators.