Neck shaping

BOTH SIDES OF NECK ARE WORKED AT THE SAME TIME, USING SEPARATE YARN
ROW 1 KNIT 23 STITCHES SLIP 23 ONTO STITCH HOLDER WITH SECOND YARN KNIT ACROSS

ROW2 AND 3 WORK ACROSS; WITH SECOND YARN BIND OFF 3 STITCHES, WORK ACROSS:(20) STS EACH SIDE I’M CONFUSED ON HOW TO BIND THE STITCHES OFF USING THE SECOND YARN CAN YOU HELP

The shoulders are worked with separate strands of yarn. K23 sts, drop that yarn, put 23 sts on a holder and with a new end finish the row. Then turn and work the next row with the same yarn, drop it and pick up the other yarn after the gap, BO 3 sts and finish working that row. Turn and begin the next row, drop the yarn, pick up the other yarn and BO 3 sts and finish the row. If you do it exactly that way, you’ll see how it works out when you get there.