An enterprise resource planning system is every information system in an organization. The enterprise resource planning system consists of the accounting system, human resource system and the information system an organization has.
It means "What is the resource used for?" So if water is the resource, the use of water is for washing, drinking, irrigating, etc. If Sunlight is the resource, the use of it is for growing crops, drying clothes, producing renewable electricity, etc.
Components that define how to get information needed within other components are input resources. A file system resource reads the information from files on the file system. Input resources include HTTP resource, subversion resource, and classpath resource.