You are (single person) eating
What are you eating?
Tu manges
(Formal) Vous mangez (Informal) Tu manges ("Tu manges un croissant" = "You eat a croissant.")
It means "What time do you have breakfast/eat in the morning?"
Est-ce que tu manges à la cantine? - Do you eat in the cantine? (ie do you have school dinners?)
qu'est-ce que tu manges?
It should be,"Tu manges avec moi, viensce soir."It means, "You're eating with me, come (over) tonight."
you're eating a lemon. Is that it?
vous mangez (formal) tu manges (informal)
when do you eat supper?
The literal translation from French is "you eat".
Qu'est-ce que tu manges au restaurant? means What do you eat in a restaurant?