No notification email (be it a welcome email or an unsubscribe confirmation) will be sent to the user if you edit it from this page.
Cancel : When clicking on this button, you return to the users listing and any modification is cancelled.
Add subscription : This button is available when the editted user has been saved at least once. Clicking this button will open a box where you'll be able to select some lists to subscribe the current user.
Save : Saves the current user and stays on the edition page.
Save & exit : Saves the current user and returns to the users listing page.
Name: Name of the user.
Email: Email of the user.
Custom fields: If you created some custom fields, they will be displayed below the Email field
Preferred language: Linked to the multilingual feature, the user will receive email in the language set in is profile
Active: This field shows you the status of the user. If you turn it off, the user won't receive messages from your website in the future.
Confirmed: If you require a confirmation, the user won't be confirmed until he clicks on the confirmation link received by e-mail. Nevertheless, if you do not require a confirmation, the user will stay as "not confirmed" but it won't impact the send process.
Tracking: If you want or not to track this user for the open and click stats
Creation date: Created date of the user.
Source : The source shows you from where the user has been created
In the first part of the history you have all the mails which have been sent to the user with some statistics.
Each user has a history saving how it has been created, how it subscribed to the lists and other information. You can use this if some bots succeeded in creating a user on your site for example, or if you need to prove that a user willingly subscribed to your lists.
When editing a user, you can subscribe or unsubscribe it from one or more lists by clicking the "Add subscription" button or the "Unsubscribe" link next to each list.