Hi, guys, my car is 2007 997.1 turbo. I just found out that my car has a oil leaks at rear left side (close to exhaust at left side). It looks like the leaks coming out form a bolt, but I am not sure. Could anybody tell is this serious problem and will cost a lot to repair? Thank you very much in advance for your advise.

assuming you have not wiped anything off I would not worry about that. it may even be cosmoline.

I have wiped clean the most part. I actually think it might be red circle part that leaks. It has been leaked small amount of oil for some time (couple drops on the floor) and I have never noticed. I will drive a bit see if there are more oil coming out from that spot.
does anyone know what hose that one is?

I drove about 100km today and there was some fresh oil around the bolt. is it simply just tighten the bolt to fix this issue? And I am not sure if the below metal pipe connection leaks or not, as there is also oil (but it could come down form above).

I would just tighten that upper bolt a tad and recheck after a drive.

The oil line is an easy fix, re the bolt I'd be very careful about tightening that beyond spec.