leak in the middle section of my engine

There is a leak in the middle section of my engine. I can spot it from the left side under the belt (3.4L engine) and directly in front. When I was under the car there is like a box and it is all covered in the fluid. I'm not sure what's leaking. It was black in color, but my oil levels are fine according to the dipstick. There is no puddle in my garage either. I have also noticed my radiator kind of smoking once I turn it off.