The "View user" page shows a user's profile, his recent tickets, his recent replies, and links to view all his tickets, either closed or "in progress". You can see the user's IP address, user-agent, assets assigned to the user, and the last time he has logged in to the helpdesk web-app.
Click the "edit" button to edit the user profile and permissions (available to administrators only or if you're looking at your own profile).
If you have enabled the "user lookup" feature, this page will show whatever information it pulled from the external source you set up in the Admin-panel. Read more about this feature here.