Mubtada and Khabar is one of those concepts that you will come across no matter where you study Arabic, or at least you should come across it.
The subject is called Mubtada, it will be in the nominative state (Marfoo3).
The predicate is called Khabar, it will also be in the nominative state (Marfoo3). The predicate is news or information about the subject. It is not description/adjective.
