It doesn't sound all that bad to me... but you must be asking for a reason. As John says ^^, is this a new car to you, or is it someone else's car etc. or is it your car which you've had for ages?
If it's your car, has the noise just appeared, or has it been doing this for a while and been getting louder?
The first thing to check is that there's enough oil in there. Open the bonnet with the engine off, find the dipstick and pull it out... Is there oil on it, and is it within the pimpled section at the bottom? If it's on the bottom mark... add half a litre of oil to the car, give it 2- 3 minutes and then check it again. You may need to add another bit of oil to get the level to the top mark. You won't need more than 1ltr.
The other thing I'd check is that the exhaust isn't blowing at the exhaust flexi section (the part of the pipe under the sump that is covered in braided steel, or looks like a concertina, if your braided steel has gone AWOL). Without dropping the car on your head or burning yourself... with the engine running, put your hand around the flexi (especially anywhere where the braided steel has a hole in it, or looks sooty) and feel for exhaust gas puffing out.
I think it'll be just low oil... which is easy/simple to solve.
Ralf S.