A production order has a unique number and holds all information necessary to fulfill a certain requirement in terms of product, quantity, delivery date, operations, BOM, etc. It is something you can schedule and eventually (when ready), send out to production for execution.
The minimum master data requirements in order to create a production order in ROB-EX Scheduler are
For a general introduction to the master data creation process read the Solving my first scheduling problem chapter.
ROB-EX Scheduler contains functionality to support creation, management and follow up of a production order in all of the life cycle steps it passes through. You can read more about this here.
This is a quick overview with links to the different sections.