Cozy dog sweater

Making this sweater and on the back it say work 3 rows as they appear

I understand the stitches but am lost on how to do this in the rows

Hi there, work 3 rows as they appear just means work the sts as you see them over the next 3 rows. So you knit the K sts and purl the P sts for 3 rows then work the cable row on the 4th row and keep repeating this.
Hope this helps, good luck with your project.