In Oracle, the word BODY refers to the part of a package that contains the code for the procedures and functions defined in the specification, and the code for private procedures and functions that are not declared in the specification. This private code is only "visible" within the package body.
The package specification defines what is contained in the package. The specification defines all public items and is the published interface to a package.
The package specification and body are stored as separate objects in the data dictionary and can be seen in the user_source view. The specification is stored as the PACKAGE type, and the body is stored as the PACKAGE BODY type.