Bardolph wants to know if a group of German guests can borrow some horses so they can meet the German Duke at Windsor Castle. (FYI—the "German Duke" doesn't actually exist. This is part of a plot where Caius and Evans try to get revenge on the Host for making fun of them at the duel.)
The Host agrees but he's not happy about, it since the Germans guests have been at the Inn for a week and haven't paid any of their bills. So he's going to over-charge them. Obviously.