The ordinance power refers to the power of the President to declare war
make laws
issue executive orders
act as chief executive

issue executive orders

Explanation:

The Ordinance power of the President refers to the President's power to issue executive orders that serve as directives to employees of the Federal government of the U.S.

As the President is the Head of the Executive, they can issue executive orders that directs the operation of the government and have the full backing of the law. Executive orders are of course subject to Judicial review which means that they must abide by the Constitution or they will be revoked.