I love a freelensed picture. They have so much character!
The pattern is a lacy cable-chevron type thing adapted from this pattern from Knitting Daily. In case you don't care about the whole pattern and just want the stitch, here's the short version:
Cast on a multiple of 12 stitches. I added two stitches because I like to have a modified edging.
ssk = "slip slip knit" = slip two stitches knitwise onto your right needle, then insert the left needle straight through them and knit them together from that position, through the backs of the stitches.
psso = "pass slipped stitch over" = as if casting off, lift the slipped stitch over the other stitch on the right needle and let it go, creating a sort of pointed three-to-one decrease.
Purl all even rows.
Row 1: yo, ssk, k7, k2tog, yo, k1
Row 3: yo, k1, ssk, k5, k2tog, k1, yo, k1
Row 5: yo, k2, ssk, k3, k2tog, k2, yo, k1
Row 7: yo, k3, ssk, k1, k2tog, k3, yo, k1
Row 9: yo, k4, sl 1 knitwise, k2tog, psso, k4, yo, k1
That's it! I create a modified edging by always slipping one stitch purlwise at the beginning of a row and knitting the final stitch of every row.