slip 1 knitwise, knit 2 together, pass slipped stitch over
Sk2p or sk2po is a left leaning 2 stitch decrease.
It sounds confusing but it’s really pretty simple.
Let’s take a look. Slip 1 stitch knitwise as if to knit it but just leaving it on your right needle. And then knit 2 stitches together, like this. You’re now going to want to pick up your slip stitch using your left needle and bring it over the top of your knit 2 together stitch and off the needle.