OEA defines a component architecture that makes it possible to reuse common components and accelerate time to value.
Within that architecture, schemas serve the purpose of defining "contracts" that allow modules to define their input dependencies.
Schemas define the structure of a set of delta tables and make it possible to "snap-in" modules based on their required inputs.
This schema catalog offers schemas that can be easily deployed to your OEA instance and hydrated either with test data or with data from your specific source systems, so that you can benefit from the modules that leverage the schema (eg, reporting modules).