Just bought a house, first time using are new washing machine(which is located on second floor) and when the cycle drained water, suds and a little water came through why shaped clean out, and a lot of water came rushing out of I'm guessing a vent that is on side of house (about 3 ft above where drain exits house) and down my driveway. After I cleaned up little water in basment looked in why shape clean out and noticed standing water. What is the reason for the standing water being so far back?(clean out is about 6 feet from trap), why did it stop there? Is that a vent that's on outside of basement wall and why did water rush out of this "vent"? Is it normal? Is the washing machine drain different from other? Please help

Are you sure what you think is a vent isn't the cleanout. Sounds like a main line blockage to me and someone left the cap off the cleanout.

Standing water in a clean out indicates a blockage downstream from it, Snake the line from the cleano out. Also purchase a new clean out cover. Good luck, Tom

Now that I think about it you're probably right it is a clean out it's just that the cap was left open because the previous owner probably had the same problem and instead of having all the water back up into his house, he open up the clean out cap(which made it look like a vent to me) so all water would drain outside and run down into the lawn. Is that possible? Cause he's a real a hole so I can see him leaving for me to take care of . Also how much do you thiink it will cost to have it snaked out? Why would the clean out be 3 feet above ground level outside? Is that maybe why water is backup becausr there's no pressure to get it up and over the pipe?

Cost will depend on time. Hard to say, hope its only a blockage and not a broken pipe. Cleanout is usually flush or 3-6" above ground. After everything is fixed, you can cut it off, install a new fitting and cap.