My main water line stubs through my foundation in my basement. There is a shut off valve located where it comes through the foundation wall. I can hear a slight hissing noise coming from the other side of the foundation. Does this mean there is a leak in my main water line? Also, when I close the shut off valve, the meter still spins.

I can hear a slight hissing noise coming from the other side.


when I close the shut off valve, the meter still spins.

Both things indicate a leak. Turn off water at meter and call plumber. Otherwise water bill will sky rocket and damage to foundation and basement wall may occur.

I agree with Harold.
You have a leak that's costing you big $. Have it looked after ASAP.
Good luck, Tom