Flashback of a table need if you update or delete some date accidentally.

1. Check the flashback is enabled.

SQL> select flashback_on from v$database;
FLASHBACK_ON
----------------------
NO

2. Enable the Row movement for table which need recovery.

ALTER TABLE HR.EMP ENABLE ROW MOVEMENT;

3. Flashback the table according to timestamp.

FLASHBACK TABLE HR.EMP TO TIMESTAMP
TO_TIMESTAMP('2021-02-25 09:00:00', `YYYY-MM-DD HH24:MI:SS');