CO on existing piece?

I am in the middle of knitting something. The piece is on the 40th row. The 41st row it says to CO (cast on, right?) 12 stitches and then knit the rest. How does one do this? I know how to increase stitches. Does this mean I get to choose my method of increasing?

It might mean to cast off, or bind off, 12 stitches. is there a stitch count you can refer to?

It sounds like you’re to cast on 12 stitches at the beginning of that particular row. What you can do is do a knitted or cable cast on and then knit those 12 as the first stitches of the next row. You could do backward loop cast on, too, but it’s not as neat looking.

It was to cast on because the stitch number increased. I knitted a cable sweater before and remembered that kind of casting on. It looks OK so I think I did it right. Thanks for the help.