The user details section provides the list of users already added to the organization. When you click on each user, you can have a detailed view of the particular user. The Admin can also perform a set of actions on the user.
In the user details section, the primary email address of the users are listed in the section. You can type in a few letters in the search box, which will return the list of matching users in the result. The Administrator can also include other profile related details, in this section.
The primary or secondary email address of the user can be used as the login email address of the user.