Do you know how can we mask value of some columns in table? For example: user A is supervisor, he can query salary column in employee table, but for user B, he is staff member, he can query salary column but system just shows ***** or something like that for salary value.
You can also do this with views. User A can be granted select on the underlying table, and see everything. User B is granted no privileges on the table, but has select on a view where the contents of salary is always NULL instead of the actual salary in EMP. (Null, because A string of ***** would cause trouble for anything expecting salary to be a number.)
Well, first off, why are you storing sensitive information in a version of Oracle that is 4 major releases out of date and has been desupported for a number of years? Upgrading to a supported version would seem like a wise choice.
Assuming that you are really stuck with an ancient version of Oracle, the previous suggestion of using views is a good one. That's likely to be more work than using VPD, potentially much more, and will be a bigger change. I would strongly suggest comparing the difficulty of that implementation against the difficulty of upgrading.