how to knit a neckline with a stitch holder

i’m having troubles understanding this pattern for a sweater. this is how it reads:
k9, slip next 10 stitches onto stitch holder for back neck, join another ball of yarn to rem sts, k9. 9stitches each side of neck opening. now working both sides at the same time, continue dec for raglan armholes on every right side row as set and at the same time, dec one st on each side of back neck on every row 5 times. continue dec for raglan armhole only until one st rem on each side.

i don’t get a few parts. first off-i put the 10 stitches onto a stitch holder and leave them there while i knot the other stitches? with two balls of yarn?
second-i decrease for the armholes, which decrease do i use? and only on the right side rows?
third-what do i do with the stitches that are on the stitch holder?
fourth-dec one st on each side of back neck on every row 5 times? does that mean dec 5 times on one row or dec once but do 5 rows worth?

i know it’s a lot of questions…i thought this would be easier to figure out. i don’t want to go too far ahead so i don’t screw something up lol…
thanks for any help!!!

Welcome to KnittingHelp!
Yes, knit across 9sts, slip 10 to a holder for the collar. There’ll be instructions later for the collar. You’ll have the first ball of yarn attached to one shoulder. Now attach a second ball of yarn to the second shoulder and knit across the remaining 9sts. You can then knit each shoulder with its own ball of yarn. So for the wrong side (WS) row, work across shoulder two to the neck edge, drop the yarn strand, pick up the yarn attached to shoulder one and work across to the armhole edge.

Use the same decrease you have been using in previous rows for the armhole edge. The pattern says “as set” which means that the raglan decreases are continuing as before. Usually this is a ssk at the beginning of the row and a k2tog at the end but do whatever you have been doing. Work these on the RS rows only, so every other row.

Every row 5x means dec one stitch on each of the next 5 rows. That’ll be RS and WS rows.

Thank you!! I’ll give it a whirl and see how it turns out.
Thanks again!