I’m trying to think of every abbreviation I might use & stuff them all here. Off the top of my head, but I’ll go through my old patterns & add more later:
BO=bind off
CO=cast on
C=cable
k=knit
k2tog=knit 2 stitches together as one
p=purl
p2tog=purl 2 stitches together as one
PM=place marker
PSSO=pass previously slipped stitch over the one you just knits (sort of as you do when you BO)
sl=slip
st/sts=stitch/stitches
SM=slip marker
SSK=slip, slip, knit (slip 2 st, one at a time, knitwise, then knit them together as one)