CREATE OR REPLACE PACKAGE pck_var
IS
   v_public_var VARCHAR2(30);
   FUNCTION get_myvar RETURN VARCHAR2;
   PROCEDURE set_myvar( piv_myval IN VARCHAR2);
END pck_var;
/

CREATE OR REPLACE PACKAGE BODY pck_var
IS
   v_private_var VARCHAR2(30);
   
   FUNCTION get_myvar RETURN VARCHAR2
   IS 
   BEGIN
     RETURN v_private_var;
   END get_myvar;  
   
   PROCEDURE set_myvar( piv_myval IN VARCHAR2)
   IS
   BEGIN
     v_private_var := piv_myval;
   END set_myvar;
END pck_var;
/

set serverout on

Begin
-- set the public variable directly:
  pck_var.v_public_var := 'Hello';
-- set the private variable through the set procedure
  pck_var.set_myvar('world');


-- display the variables
  dbms_output.put_line( -- get the public variable directly:
                        pck_var.v_public_var||' '||
                        -- get the private variable through the function
                        pck_var.get_myvar
                      );
End;
/

DROP PACKAGE pck_var
/