The Create Business Components from Tables Wizard: Application Module
On the Application Module page of the wizard, you designate whether to add the business components that you are creating to an application module. Application modules enable you to test business components and also to expose them to a user interface.
If you choose to use an application module, you can create a default one or specify an existing one to contain instances of all the view objects, joined in a master–detail hierarchy in every possible way by the view link instances that the wizard is creating.
If you are creating a new application module, you specify the name of a package to contain it, and you give the application module a name.