In need of help with a pattern

I am knitting a sweater for my boyfriend and I am a bit confused by the pattern.

The point where I got confused:

”Next row Bind Off 13 sts. work until 17 sts on RH needle, turn and work on these sts only for first side of neck.

Bind off 4 sts at beg of nect row.

Bind off rem 13 sts.

With Rs facing, slip next 40 sts onto a holder, rejoin yarn to rem sts and work to end of row. Complete to match first side, reversing shaping.”

I am so in need of help from someone to explain what to do next!

Work only on the 17 sts, turn and work across, turn and BO 4 st at the beg of the next RS row, turn and BO the remaining sts. Take a new end of yarn, knit the rest of the sts to the end of the row. Turn and BO 13, then knit 17 sts, turn and knit to the end of the row, turn and BO 4 sts, work to the end of the row, turn and BO 13 sts.