Celtic Knot Stole - Knitting Chart Question

I am working on the Celtic Knot Stole (http://www.fileden.com/files/2006/11/25/418882/Celtic%20Knot%20Stole.pdf) but don’t understand one of the stitches in the key.

The instructions in the key state:
“join stitch together with one body stitch with an SSK decrease”

I don’t understand what this means. It might become more clear once I actually get to that point in the chart, but I’d like to have SOME idea ahead of time.

Can anyone help?

It just means you’re joining the border and the body together-Slip one stitch to right needle and knit it together with the stitch that was already on your right needle before you slipped a stitch.You’ll see it better when you are doing it.It will make sense as you go along.The shawl is Beautiful you’ll have to show pictures when it’s done