what is meant by package

A package is a collection of PL/SQL elements that are "packaged" or grouped together within a special BEGIN-END syntax, a kind of "meta-block."

Packages bundle related PL/SQL types, items, and subprograms into one container.

A package usually has a specification and a body, stored separately in the database.

The body fully defines cursors and subprograms, and so implements the specification.
The package itself cannot be called, parameterized, or nested. Still, the format of a package is similar to
that of a subprogram. Once written and compiled, the contents can be shared by many applications.
When you call a packaged PL/SQL construct for the first time, the whole package is loaded into
memory. Thus, later calls to constructs in the same package require no disk input/output (I/O).

You create a package in two parts: first the package specification, and then the package body. Public
package constructs are those that are declared in the package specification and defined in the package
body. Private package constructs are those that are defined solely within the package body.

A package is a collection of related program objects like procedures, functions, cursors and exceptions.

Main advantages of using packages is
It reduces Disk I/O operations.
Packages grants privileges more efficiently.
Packages supports OOPS features.

The sytax for calling a Package at SQL Prompt is
Exec Package_name.Procedure_name(Parameters)