入り口

How it works

は (topic) raises 入口いりぐち (entrance) as the topic — “as for the entrance…”. No verb is needed: the location word あちら (over there) names where it is, and polite です (is) closes the sentence. あちら (over there) is the formal, distal “that way” — politer than the casual あっち (that way), which suits helping a guest.