Rawrcookie
6 strings are easier to learn on and grasp the basics. 12 string guitars would be difficult for a beginner; the difference between sound is immense, and would take a lot of hard work to master.

rtrentmartin
Go with a 6-string. It's easier to string and tune a 6-string, and easier to play for a beginner. Good luck!

OnTheRock
You should definitely learn on a 6 string. A 12 string is played the same as a 6 string but the strings are doubled (2 strings close together). Because of that the neck is wider, it's harder to fret the strings with your left hand, and it's more difficult to pluck the right string with your right hand. I would never advise a beginning guitarist to learn on a 12 string guitar. Once you learn to play though, a 12 string is great. It gives a nice full sound with the lower 4 strings being tuned in pairs an octave apart. Definitely not what you want to learn on though.

M
Learn on the 6-string. Get a 12-string when you're ready for it. And dip your fingertips in rubbing alcohol after you're done playing. You will build up callouses really quick.