Casting on in the within the project

I’m on Row 56 of a pair of Bella Mittens and the directions tell me to cast on 2 stitches after knitting 2…the next direction reads
" cast on 2 stitches, k12, M1, k2…"
Do I cast them on the left needle and then is it implied that I knit them before I do the K12…that’s the only way I can make the math work and follow the pattern

You cast them on to the right needle and don’t knit them until the next round. So you CO, k12, m1, and continue on with the rest of the round. You can do a backward loop CO, or move the needle to the L hand, do a knit CO (knit into the first st, leave it on the needle and put the new st on the needle) then move them back to the R hand to finish the round.