SQL> show parameter timed

NAME                                 TYPE        VALUE
------------------------------------ ----------- -------------
timed_os_statistics                  integer     0
timed_statistics                     boolean     TRUE


And see the result of the following statement
SQL> select * from scott.emp;

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      7369 SMITH      CLERK           7902 17-DEC-80        800                    20
      7499 ALLEN      SALESMAN        7698 20-FEB-81       1600        300         30
      7521 WARD       SALESMAN        7698 22-FEB-81       1250        500         30
      7566 JONES      MANAGER         7839 02-APR-81       2975                    20
      7654 MARTIN     SALESMAN        7698 28-SEP-81       1250       1400         30
      7698 BLAKE      MANAGER         7839 01-MAY-81       2850                    30
      7782 CLARK      MANAGER         7839 09-JUN-81       2450                    10
      7788 SCOTT      ANALYST         7566 19-APR-87       3000                    20
      7839 KING       PRESIDENT            17-NOV-81       5000                    10
      7844 TURNER     SALESMAN        7698 08-SEP-81       1500          0         30
      7876 ADAMS      CLERK           7788 23-MAY-87       1100                    20

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      7900 JAMES      CLERK           7698 03-DEC-81        950                    30
      7902 FORD       ANALYST         7566 03-DEC-81       3000                    20
      7934 MILLER     CLERK           7782 23-JAN-82       1300                    10

14 rows selected.


Execution Plan
----------------------------------------------------------
   0      SELECT STATEMENT Optimizer=CHOOSE
   1    0   TABLE ACCESS (FULL) OF 'EMP'




Statistics
----------------------------------------------------------
          0  recursive calls
          0  db block gets
          0  consistent gets
          0  physical reads
          0  redo size
          0  bytes sent via SQL*Net to client
          0  bytes received via SQL*Net from client
          0  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
         14  rows processed

SQL> 

SQL> select * from emp;

15 rows selected.


Statistics
----------------------------------------------------------
          0  recursive calls
          0  db block gets
          4  consistent gets
          0  physical reads
          0  redo size
       1337  bytes sent via SQL*Net to client
        499  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
         15  rows processed



SQL>  update emp set ename='TEST1' where empno=7934;

1 row updated.


Statistics
----------------------------------------------------------
          0  recursive calls
          1  db block gets
          1  consistent gets
          0  physical reads
        244  redo size
        624  bytes sent via SQL*Net to client
        542  bytes received via SQL*Net from client
          3  SQL*Net roundtrips to/from client
          1  sorts (memory)
          0  sorts (disk)
          1  rows processed

  1* insert into emp(EMPNO) VALUES(9000)
SQL> /

1 row created.

Statistics
----------------------------------------------------------
          0  recursive calls
          3  db block gets
          1  consistent gets
          0  physical reads
        420  redo size
        624  bytes sent via SQL*Net to client
        531  bytes received via SQL*Net from client
          3  SQL*Net roundtrips to/from client
          1  sorts (memory)
          0  sorts (disk)
          1  rows processed




SQL>SELECT * FROM EMP;

statistics
------------------------------------------------------
      0  recursive calls
      0  db block gets
      4  consistent gets
      0  physical reads
      0  redo size
   1467  bytes sent via SQL*Net to client
    510  bytes received via SQL*Net from client
      3  SQL*Net roundtrips to/from client
      0  sorts (memory)
      0  sorts (disk)
     16  rows processed



SQL> DELETE FROM EMP
16 rows deleted.

Statistics
----------------------------------------------------------
          0  recursive calls
         50  db block gets
          3  consistent gets
          0  physical reads
       7464  redo size
        624  bytes sent via SQL*Net to client
        512  bytes received via SQL*Net from client
          3  SQL*Net roundtrips to/from client
          1  sorts (memory)
          0  sorts (disk)
         16  rows processed