what does this mean?
It means slip the first stitch purl-wise. To do that you stick the right needle right into the first stitch as if you’re going to purl and slip it to the left needle.
Here’s a video showing you both purl-wise and knit-wise. The one you want to learn is about halfway through the video.
And purlwise/knitwise only refers to how you insert the needle, not where the yarn is.