I found directions for it:
Its to get a hole between two purl stitches.
Take the yarn over the top of the needle, then between the needles to the front again before purling the next stitch.
So (my translation since I have a picture here) You start with the yarn in front as if to purl as normal. Bring it up over the top of your right hand needle to the back and around to the front, essentially wrapping the yarn around the top of the needle. Then purl the next two stitches together in your case.