This is a simple timer. In programming the job of a timer is to run code after "X seconds have passed".
So it could help you to know that you have been logged in (on this char and not reloaded the UI) for X ammount of time.
We got 2 dedicated Clock addons. Look if they have a functionality like this:
http://www.esoui.com/downloads/info2...ndardTime.html
http://www.esoui.com/downloads/info232-TamrielTime.html
I am not sure how precise thier values or moon phase prediction really is.