in length. The 34/35 is an indication that someone who wears a 34 or a 35 can wear the shirt.

The combo sleeve lengths are typically used by mass manufacturers who are looking to cut down on different sizes that they would otherwise need to carry. They'll make a 16-32/33 which has a 32.5 inch sleeve and a 16-34-35 that has a 34.5 inch sleeve. By making two sizes of shirts, they cover four different sizes. If you go with higher end shirts, you don't see the combo sleeve sizes. Rather you get sleeve sizes in one inch increments.