New to knitting

Hello. I am just starting to knitt. I am trying to make a chemo hat and I do not understand pattern instructions. What does the numbers in () mean?
Round 1:*knit8 (9,10), k2tog;repeat from to end of round

The numbers between the () are to tell you how many stitches to work for a particular size. In your case, the 8 would be the smallest size and the 9 and 10 would be for the next two sizes.

Thank you, Ingrid