Knitting pattern - what does this mean?

Hi can you tell me what this means:

Rep the last 2 rows for 12cm ending with a 2nd row

it’s from this part of a pattern for a collar:
1st row (WS) P2, * k2, p2; rep from * to end.
2nd row K2, * p2, k2; rep from * to end. Rep the last 2
rows for 8(8:9:9:10)cm ending with a 2nd row.

thanks in advance

You should repeat row 1, row 2, row 1, row 2, etc (or whatever the last 2 rows are numbered) until you’ve knit about 12 cm and end after you knit a row 2.

this would be a good time to explain ‘reading’ your knitting. if you look at a stitch and it looks like a V, then on that side of your work it is considered a knit stitch. If you see a bump immediately under the needle, then on that side of the work, it is considered a purl stitch.

Once you understand this, you can memorize this simple pattern. (I’m assuming you cast on an even number of stitches) Look at your first 2 stitches? if they look like V’s, you want to knit them and then P2 etc across. if they have bumps, you want to purl them and then K2 etc across.

basically you end up with blocks of knit and pull stitches, 2 stitches wide but 2 rows tall.

I hope that makes sense. Learning to read your knitting will serve you well because if you put down your knitting in the middle of a row, you’ll be able to tell exactly where you are and what you need to do.