Fine dining has become a hobby for many people, so it makes sense to acquire the necessary vocabulary. Because the English-speaking countries were for a long time not exactly known for their exquisite food, many of the expressions are in fact of French origin.
An amuse-bouche or amuse-gueule (listen here) (known as Gruß aus der Küche in German) is an appetizer served for free to get the customer in the mood for food.
Confusingly, an entrée (listen here) can either be the main dish of a meal (in American English, Hauptspeise in German) or a dish before the main dish (in British English, Vorspeise in German). Remember that when you are looking at a menu (not card, for my German-speaking readers) in the US trying to find the main courses!