What is judicial power?

The power of a court to hear a case involving a dispute/conflict (courts exist solely to resolve disputes). Judicial review is most often associated with the concept of judicial power; and it is the power of a court to invalidate or legitimate an act of Congress (or in some cases an act of a state legislature) with regards to a written constitution.

in theory, the judiciary is not to make law, but interpret it. judges however have a tendency to make law from the bench. Brown vs Board of Education is a great example.