Armholes

I have started a sweater pattern and having troubles understanding the pattern . it says

shape armholes:cast off 2(2-2-2-3-3)sts beg next 4 (4-6-8-8-10) rows. 31(35-35-36-36-38) sts

can anyone please help to explain it to me
andI also did shape shoulder cast off 8(9-9-9-9-10)sts loosely beg next 2 rows. leave rem15(17-17-18-18-18)sts on a st holder. I did all that now im stuck on front
work toas given for the back,beg armhole shaping on same row of stripe pat as back. then it goes to shaping the neck. do i start the front a new ?

The different numbers are for the different sizes, so bind off however many for your size (2 or 3) at the beginning of the next whatever rows. The final number is how many sts you’ll have left after binding off the rows.

I thought so but. dont i need to bind off both sides of the row? im having troubles getting the arm holes to line up or i make a big hole at the end of the row… thanks for such a fast reply

You can’t BO at the end of a row, so you do it at the beg of the next row. That makes a BO on both [I]sides[/I] of the piece, which is what is needed. Try it and see how it works.