What does sn in crochet mean - Sewing Machines

Hello, Joyce -

I am not familiar with the crochet stitch abbreviation "sn". Did you mis-read the abbreviation, perhaps? Or, maybe there is a typo in the crochet instructions.

There is the crochet stitch abbreviation "sh" which stands for "shell" - a shell stitch.

See this tutorial for the shell stitch:
https://www.thesprucecrafts.com/how-to-crochet-a-shell-stitch-979096

This is a link to a master list of crochet stitch abbreviations for North America:
https://www.craftyarncouncil.com/standards/crochet-abbreviations

I suggest you contact the source of the crochet instructions and verify if "sn" was meant or not.

Best wishes.