I can’t figure out how to do this…
P to last 3 sts., turn, k back (counts as Row 4). This makes a dec row.

Can anyone give me some advice?

It makes a short row. Purl across and when there’s 3 sts on the left needle, turn your work as if you were at the end of the row and knit back over the sts you just purled. You’ll knit the last 3 sts later on.

I am making a snowman family and when i got to that in the directions I was completely stuck!
I can’t wait to finish them off.