Você não usa INTO com um cursor implícito:
DECLARE
emp_dept_id employees.department_id%TYPE;
emp_emp_id employees.employee_id%TYPE;
emp_last_name employees.last_name%TYPE;
v_count number DEFAULT 0;
BEGIN
FOR i IN (SELECT DISTINCT department_id, department_name
FROM departments)
LOOP
--v_COUNT := v_COUNT + 1;
DBMS_OUTPUT.PUT_LINE('HELLO'||i.department_id||' '||i.department_name);
FOR j IN (SELECT employee_id, last_name
INTO emp_emp_id, emp_last_name
FROM employees)
--WHERE department_id=i.department_id)
LOOP
DBMS_OUTPUT.PUT_LINE(emp_emp_id||' '||emp_last_name);
v_COUNT := v_COUNT + 1;
END LOOP;
END LOOP;
DBMS_OUTPUT.PUT_LINE(v_COUNT);
END;
/
