Hyundai now has an N division... what the hell is the N referencing?

It's either Namyang South Korea,
or it's Nurburgring, where the test and tune the prototype before going to production

Or, it's the letter after M... as in BMW's M series

https://autoweek.com/article/frankfurt-motor-show/hyundai-launches-racy-n-division-frankfurt-motor-show