Knitting pattern question for sweater

I am knitting a sweater and I don’t understand the instructions in this whole section:

(RS] (dec) Dec 1 st at neck edge of this row,
then foll10(12,14,16,18,20)rows
[19(21,22,26,27,29]sts,12(14,16,18,20,22)
neck shaping rows].
Cont straight until length from beg armhole…(this last sentence I get)

Welcome to KH!

On the right side row (RS) decrease one stitch at the neck edge on every row for the number of rows given for your size. So if you call the current row (“this row”), row 1, for the smallest size you would decrease on rows 1,2,3,4,5,6,7,8,9,10 and 11. You’re left with 19 sts and after working the next wrong side (WS) row or having worked an earlier dec row, will have worked 12 rows.

What is the name of your pattern?

Thank you so much! It’s the garter stitch jacket I downloaded from lovecrafts

Very nice!