你吃饭了吗？(Have you eaten?) is a traditional Chinese greeting, showing concern for the other person's well-being. It doesn't necessarily require a literal answer.
usage
饭 can mean either cooked rice specifically or a meal in general. 吃饭 means to eat (a meal), 做饭 means to cook, 早饭/午饭/晚饭 = breakfast/lunch/dinner.
