There is a mistake in the original pattern upload :
Knit chart C 4 times, not 3 times. A corrected version has been uploaded.

The pattern contains charts with minimal written instructions.

Hourglasses can be knitted with both wool and cotton yarn. The yardage and weight of the yarn and needle size determines the size of the final shawl. As such, the given gauge is irrelevant.

I used 3 skeins of the wool yarn and 4.5 skeins of the cotton yarn.

Sizes with my chosen yarns:
185 cm wide, 80 cm from top to the tip (wool shawl)
190 cm wide, 85 cm from top to the tip (cotton shawl)

Gauge for the wool yarn is 15x28 stitches
Gauge for cotton yarn is 16x26/28 stitches

To knit the shawl you need to know how to :
Read a chart
Cast on backward loops
Knit
Purl
K2tog (knit 2 together)
K2togtbl (knit 2 together through the back loop)
S2kp (sl2-k1-p2sso) : slip 2, knit 1, slip 2 over
OR
k3tog (knit 3 together)

The pattern includes a photo tutorial for the tab cast on

If in doubt about needle size, knit pattern chart A and B to see if you are happy with the look of it. Change needles if not.

I recommend using the largest size needle recommended for your chosen yarn. Go up another needle size if you are a tight knitter. Use the smallest size recommended if you are a loose knitter.