Adding an email form will enable your end users to get in touch with you (or your contributors, advertisers, etc.) via an embedded interface.
The Tracking Name is an arbitrary name, not visible to end users, that auto-fills future instances of this same email address. For example, if you are adding a link to firstname.lastname@example.org in the Email field, you might use "Hello" for the Tracking Name. In the future, you can just type the first few letters of "Hello" and the editor will auto-fill the email address for you.
No Repeat simply means that this email link will not repeat in the same place on future pages. If you would like it to, click it for a drop-down menu that allows you to select from the options "All Pages," "All Except," and "Every Other" (each taking effect from the current page forward, not in reverse).