Question

What does this mean: "What can I do for you ?"

Answer 1

Hint: What can I do you for is a phrase. A phrase is a small group of words that stand together as a conceptual unit, usually as a clause portion.

Complete answer:
"What can I do for you?" is a phrase. A phrase is a collection of words that form a grammatical unit, usually as part of a clause or a sentence.

What can I do for you? is a play on words. This implies or indicates assisting others, such as in a store.
How can I help you, particularly financially, according to the phrase above? It suggests some kind of deception, since it sounds like an expression of good intentions, but a slight reversal of just two words means the exact opposite.

If I'm a teacher and a student approaches me, I might say one of these things, but they don't mean the same thing. "What can I do for you?" is certainly more polite and nicer, because we're wondering if there's anything we can do for them that they don't, like sign a permission slip.

Note: In the 1930s or 1940s, a British comedy radio show popularised the phrase "what can I do you for?" Mrs Mopp, a housekeeper character in the show "ITMA" (It's That Man Again) at the time, had the catchphrase "can I do you now sir?" It was intended to be funny. The phrase "what can I do for you" has become more prominent.