It's a common greeting, particularly in the morning or afternoon. It's similar to "Have you had breakfast/lunch?" in English, but it's not always meant to be taken literally. It's often just a friendly way to show concern for someone's well-being.
Here's a breakdown of the characters:
* 你 (ni): you
* 吃 (chi): to eat
* 饭 (fan): rice/meal
* 了 (le): past tense marker (indicates the action has already happened)
* 没 (mei): not
* 有 (you): have
So, the literal translation would be "Have you eaten rice?" but it's understood to mean "Have you eaten anything?"