Object 
An object is a unit (Business Object) combined from the business point of view, which is used to transfer the data of a project to the SAP system.
An object consists of the following elements:
Tables involved in the project and in the SAP system
Structure(s) for transfer of data
Relationship between data at the table and field level (structure relationships)
Field assignments for conversion of data
An object is assigned to a subproject. For example, customer master, material master, or financial documents are objects.