Why does the following PL/SQL block fail to execute successf…

Why dоes the fоllоwing PL/SQL block fаil to execute successfully? DECLARE  v_nаme1 VARCHAR2(20);BEGIN   DECLARE v_nаme2 VARCHAR2(20);   BEGIN         DBMS_OUTPUT.PUT_LINE(v_name1);   END;   DBMS_OUTPUT.PUT_LINE(v_name2);END;