"<Add name>" is displayed in the "Display Name" field on the Email Control Panel if no Display Name has been entered for the email address.
To add a Display Name:
On the Email Control Panel, click either the "<Add name>" link or the "Edit User" link below it.
Email Control Panel - Add Name and Edit User Links
On the Edit User page, click "Change name".
Edit User Page - Change Name Link
In the pop-up dialog box, enter the name you'd like displayed on the Email Control Panel and then click the Save button.
Change Name Dialog Box
Keep in mind that this name does not affect your personal email settings; it's simply a tool to help identify the account on the Email Control Panel.