The cables are knit sts and in between you have the p6 sts to separate them. That's in this part -
"Start knitting in the round where you joined (this should be at the beginning of one of your ear flaps.) P6, K12 around until the body of the hat measures 6.5 to 7” long."
But first you start out with 6 sts for the ear flaps and that's where you begin the chart. K6 for a couple rows (actually you're knitting flat so you knit a row, purl a row) then on R 3 k2 and work the cable. Work in stockinette for the next 3 rows then cable and k2. Go on up the chart and after 6 inches inc 3 sts from 6 to 9. Then work the 9 sts in the cable patt - k3, cable over the next 6. Work the chart some more, then inc to 12 sts and work that cable pattern, then inc gradually as stated in the pattern, but the new sts will be in purl. When you have 24 sts there will be 12 in middle in knit for the cable, and 6 p sts on either side of it. After that go on to the body sts.