means to insert your needle as if to purl it and slip it to the right needle without purling it.
means to slip, knit, pass. This is a decrease. It means you will slip one stitch, knit the next stitch, then pass the slipped stitch over the knitted stitch. There is a video here showing you how to do it. It's the 3rd one down on the right hand side. http://www.knittinghelp.com/videos/decreases