Definition:
In Oracle PL/SQL, PRIVATE is a reserved word which is used to categorize local subprograms or PL/SQL constructs used within a Package Body. The scope and visibility of a Private construct is the Package Body. They cannot be referenced from an external program unit.
Besides the above context, all synonyms and database links are created as Private by default, unless explicitly created using PUBLIC keyword. Private schema objects can be accessed by the object owner only.