how to slip a stitch purlwise (sl1p): in, off

in - insert your needle in the front of the stitch, approaching from the right side

off - slide the stitch from the lefthand needle to the righthand needle

how to pass a slipped stitch over (psso): in, over & off

in - insert the tip of your lefthand needle into the second stitch on your righthand needle, approaching from the left side

over & off - lift the second stitch over the first stitch using your lefthand needle and off the righthand needle