Beginner needs help reading a pattern
I am in the process of knitting a pull-on hat. This is my first knitting project and I need some help reading my pattern. I have knitted three and 1/2 inches of a 2 x 2 rib. K2, p2. I am getting confused on the next row. My pattern shows three sizes and I am knitting the third size. These are the directions. Could someone walk me through please?
P2 [3:2], p2tog, (p6 [5:4], p2 tog) 5 [6:8] times, p2 [3:2]. 40 [43:45] sts.
I am thinking that I
purl 2 together
purl 4, purl 2 together (8 times)
not sure what 40 [43:45] sts means (?)
Thank you for any guidance you can give.