"I eat French food."
Translation:Fransız yemeği yerim.
It's the not in the accusative case. Most of the time, words denoting a nationality, form compounds with the next word. "Alman arabaSI" (German car) ; İtalyan evi (Italian house)" etc. It's kind of like saying: "Car of the German people" ; "House of the Italians" :-]
Fransız yemeği = French food (lit. Food of the French)
In the accusative, it'd be: "Fransız yemeğini".