Pullover -- neck

This question might be very trivial, but I am a new knitter and am knitting a pullover for the very first time. I got completely stuck at the “shape shoulders and neck” stage (it’s the back).
This is what the pattern says:
“Shape Shoulders and Neck: Bind off 4 sts at beg of the next 2 rows.
Next Row (RS): Bind off 3 sts, k until there are 4 sts on RH needle, join another ball of yarn and bind off center 32 sts, k to end. Working both side at once, bind off 3 sts at beg of the next 3 rows. At the same time, dec 1 st at each neck edge on next WS row.”

So. I do understand the abbreviations here, but… basically nothing else. How many sts should I bind off in the 1st row that is coming? 3 or 4? Does “until there are 4 sts on RH needle” simply means k4? Do I simply abandon the old yarn there, and start with a new one to bind off the center sts?
Is the neck edge the very first st. before/after the neck?

Thank you very much for any help.

First BO 4 sts for 2 rows, then 3 sts on the next rows, knit 3 more sts (with the st left from the BO, that makes 4 sts) and with another yarn end, BO 32 sts in the middle and finish the row. Now each shoulder has it’s own yarn. Turn and BO 3 at the beg of the ws row and work to the center, dec a st, drop the yarn and dec then finish the row. Turn and on the RS, BO 3 sts and I think that’s all that there are, drop the yarn and knit the last sts, turn and bind them off.