DECLARE
   v_var1 v_type;
   ...
BEGIN
   -- PL/SQL
END;

Example: DECLARE
            v_name Varchar2(20);
            v_salary employees.salary%TYPE;
         BEGIN
            SELECT name, salary INTO v_name, v_salary FROM employees WHERE employee_id = 100;
            DBMS_OUTPUT.PUT_LINE('Name: ' || v_name || ', Salary: ' || v_salary);
         EXCEPTION
            WHEN NO_DATA_FOUND THEN
               DBMS_OUTPUT.PUT_LINE('No data found.');
         END;