OK, the directions are:
K27 sts [left sleeve] and leave on needle. **Turn, purl into front & back (F & B) of first st, purl to last st,
purl into F & B of last st: 29 sts.
So you're going to be working on the 27 sleeve sts. Turn so that you're on the purl side and increase one st by doing a purl into the front and back of the stitch. Then purl across to the last stitch and increase one st in that last stitch by the purl front and back. In total you'll increase 2 sts on that purl row for a total of 29sts by the end of the row. Cute pattern!