Hello Sarah, that mean your hands length, and our tailor will make the sleeves by proportion (as the product photo shown, the short sleeves is about half of the hands length).
If you have special request on the short sleeves length, we can change the length for you, just write it in remark box (in order form), and our tailor will adjust it for you. n_n
*Remark message like 'I want a shorter white sleeves, from shoulder to white sleeves' end: xxcm.'