The most common form of this expression is “밥 먹었어요?” To review when to use each form above, see my lesson on politeness levels.
In Korean, 밥 literally means rice, but it also translates to food in general. 먹었어 is the past tense conjugation of the verb 먹다, meaning “to eat.” Need a refresher? See my lesson on past tense conjugation.
You can add the object marker “을” to 밥, like I did in the formal example above, but in conversation this is often omitted. See my lesson on the object marker for a refresher.
There is also an honorific version of this phrase:
It uses the honorific 시다 ending, meaning the unconjugated form of the above would be 식사하시다 (식사 means “meal”). See the lesson on honorifics here.