According to Wikipedia:
A yard is a spar on a mast from which sails are set. It may be constructed of timber, steel, or from more modern materials, like aluminum or carbon fiber. Although some types of fore and aft rigs have yards (see below), the term is usually used to describe the horizontal spars used with square sails. In addition, for some decades after square sails were generally dispensed with, some yards were retained for deploying wireless (radio) aerials and signal flags.Then I have learned something new today :-)
BTW, The ship with these yards was a usual the barque Statsraad Lehmkuhl.