Rear passenger side leak

I was told I need to replace my cyphus tube, dryer and compressor, besides that on the passenger side rear just in front of back tire under the car is a slow dripping leak. It is clear fluid and smells like hot urine or belly button, anyway there are 2 pipes, to help you narrow it down out out of the 2 one has rings on it not that one, but the other one without rings on it. That pipe has 2 a total of 2 pipes cuz it has a gasket holding them together, I think, you cant see in pic but it would be on left it got cut off in picture, there is small dripping leak from the gasket part that looked light green before the drops fall to the ground was green but on the ground puddle I see no green, but the other end of the pipe that goes near the wall body (right side of pic)of the car looks like a oversized spark plug has clear water drops leaking? I noticed my coolant is always low what is this pipe called and is there a connection between anythign going on with my van? What should I do what is this? Please? I sent a picture so its the shiny slimy black pipe on right