It is Lallans scots, which is English very much as Chaucer would have recognised it. Translation - "Well, you know now."
There is a story that a meenister (sorry, minister) preached one day of a sinner who found himself up in front of God. God spoke of all he had dome wrong, which was a lot, and harangued him for a long time about how wicked he had been, and how he would now have to account for all his misdeeds, which would probably get his consigned to the Other Place. (I wish I could type as it was said, it sounds much better).
The sinner was aghast. OH Lord! he said, spare me, spare me. I didna ken!"
"Weel", said God."Ye ken noo!"