What does it mean when your pattern says cast off sts?

I am working on my very first non-scaft and non-purse project. I am making a teddy bear sweater. When the pattern calls for armhole shaping, it says to cast off 4 sts at the beg of the row. I’m not sure what it means. Should I bind off those sts or does it mean something entirely different. I would appreciate any help I could get.

It means to bind off the first 4 stitches

Thanks. lovestoknit. I’m slowly building up my personal glossary of knitting terms.