"Yuns" is the Arkansas hillbilly version of y'all.
As far as I can tell, it's a contraction of "you ones".
Here is the true story of how I learned this. (And I've left the more unbelievable elements out.)
The first time I heard it was the first day of school when we moved to the Ozarks to become hillbillies (voluntarily and on purpose, but not permanantly as it turned out.)
Hillbilly kid on the school bus, to my brother and me: "Where do yuns live?"
Me, bewildered (in the most literal sense, actually), and thinking "yuns?, what the hell is a yun? How the hell should I know where they live. Maybe they live in caves and eat cherries for all I know.: "Huh?"
This repeats a few times, with me saying "Huh?" each time, and then:
Hillbilly kid: (finally exasperated by my inability to comprehend simple English) "Yuns talk funny!"
Yeah, I suppose yuns do talk funny.
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