This is the 640th most frequent Chinese word.
哪里
"哪里" means "where."
The usage of '哪里' here is to ask about a place or location in interrogative form.
这是哪里？
Where is this?
The usage of '哪里' here is to ask about the destination of someone's action.
你要去哪里？
Where are you going?
The usage of '哪里，哪里' here is an expression of modesty when receiving praise, meaning 'not at all' or 'you flatter me' in a polite manner.