What kind of kale is this?
It's just a variant of kale, part of the genus Brassica. I think you'd call this particular variant redbor or purple, bluntly, but you could go further because kale is often classified by the type of leaf. So in your picture, curly 'redbor' or 'purple' kale.

This is your specific name: Brassica oleracea Acephala Group.

(just sort of look at wikipedia)