Low oil pressure

Hi to all,

My car displays low oil pressure on the screen. What could cause the problem as there is oil in the engine and sounds nice and smooth while works?

Another problem is parking brake fault.
When I and turn it off then apples the parking brake (but the light which should turn on does not turn on ) automatically as it should I think. then later if you want to release that, the handler does not release the parking brake.
Then a message applets say parking brake fault.

Thanks in advance.