Singer asks girl to go with him. He points to shepherds and soldiers marching, and the snowy hills, which parted many lovers and will part them. Refrain: "Busk, busk, bonnie lassie, and come alang wi me/I will tak' ye tae Glenisla near bonnie Glenshee"
No relation to "Lass of Glenshee." - PJS
To busk, in this context, is to prepare to travel. - PJS, RBW