Pattern is written in US crochet terms.

This pullover is worked from the bottom up in 4 pieces (front & back panels, and sleeves) and then seamed together, seaming one shoulder seam in further than the other to create the off-shoulder neckline.

Sizes are referred to in order when given instructions in parentheses throughout the pattern.
26-28(30-34, 36-40, 42-46, 48-52, 54-58, 60-64)”

I highly recommend a yarn that has some drape and stretch (including fibers like bamboo) for fit as shown.