Some OpenMRS functionality is pulled out into modules instead of being written into the core application. This allows users to upgrade the content in those modules without having to wait for the next OpenMRS release.
Core modules are sometimes confused with Bundled Modules which are simply included in the release downloads.
Disabling a core module could corrupt your database and break your instance of OpenMRS. This should never be done in a production environment and should only be used by experienced developers.
You can add module.ignore_core_status=true to your runtime properties file. NEVER DO THIS ON A PRODUCTION SYSTEM as it could corrupt your data or break your instance of OpenMRS. This is a special property used for some unit tests and/or by experienced developers during development & testing of OpenMRS.