Need help with pattern

Hi all,
I’m new here, so not sure if I’m asking this in the right section…but here goes:

I have a question about a pattern I’m following. I’m trying to write it out in steps so I can follow, but I’m not sure I’m reading it right. It’s a baby sweater-Rowan’s “Just Baby” book, Norton pattern in case anyone has this.

Here’s the part I’m stuck on. Working on the back of the sweater, I’ve started shaping the raglan armholes.
Have done this one:
Next row (RS) K2, K2tog, K to last 4 sts, sl 1, K1, psso, K2

But here’s where I’m stuck and need a translation:
Working all raglan armhole decreases as set by last row, dec 1 st at each end of 4th and 2 foll 4th rows, then on foll 9 alt rows. [29] sts

Thanks in advance to anyone who can help me!

Hi and welcome!
So if the decrease row you’ve just done is called row 1 then you would decrease on rows 5, 9, and 13. Then on the following 9 alternate rows (rows 15,17,19,21etc). There’ll be 29sts on the needle after the last decrease row.