You have 120 stitches and this chart is worked over 12 stitches and repeated 10 times around the hat. Since you are working in the round you read all rows right to left (just as you knit all rows right to left). Each box with nothing in it is a knit stitch. The boxes with the little "o" in them represent yarn overs. A yarn over is really between stitches, but just do it just as written and yarn over when you come to a box with a "o". The only other symbol is the tepee thing with 3 legs coming down. That maneuver (the double decrease) really uses three stitches, but that is all figured into the chart so that it works. When you come to the tepee slip 2 together knitwise, k1, and slip the 2 slipped stitches over that knit and off the RH needle tip.
You begin at the bottom of the chart and work up. The first row read right to left tells you to: K1, yo, K4, do the double dec, K4, yo. You end that row with a yarn over, so you don't have any stitches left in that first group of 12, but you don't need any because it is a yarn over.
The next and all the even rows you just knit across.
Row 3 is: K2, yo, K3, D dec, K3, yo. k2. (D dec=double decrease)
Do you see how it is working?
Row 9 the last row of the chart that is not just a knit row is:
K5, yo, D dec, yo, K4.