The idiom "feel like something/doing something" is used in an informal way both in American and British English. When you have a wish, desire or inclination for something, you can use it in a normal way. It's nothing to do with politeness or impolitenesss. Besides, its use in the form of a question is seldom. The usual and polite way for offers and invitations is using "would" such as "Would you like a coffee?" or "What would you like to drink?" or "Would you have dinner with me tomorrow?".
I don't mean that you can not say "Do you feel like some coffee?" There is nothing wrong with it grammatically. What I mean is that we use this idiom in an ordinary way. It's just like when you ask somebody "Are you in the mood for dancing?"
It's a normal way of speaking.
From original question
I thought only " what does@@mean?"was grammatically correct but I heard a lot of Americans saying "what does it mean by @@?"
If you saw something confusing on a street sign, you might point and say "what does it mean by that".
Here, "it" would refer to the sign. You are treating the sign as if it were a person who had said something. So it's very similar to sentences like "What did he mean when he said that?"
This isn't particularly common. If you are reading and trying to understand a book that has a lot of confusing sentences and it's like the book itself starts to take on an evil identity...it might be more common. :-)
As for "What does it mean that (...)", there are rare cases you might hear it as a kind of question to provoke thought, where you're not expecting an answer (e.g. a "rhetorical question".)
- "What does it mean that one fourth of humanity lives without electricity?"
But if you're really asking about what something means, "What does (...) mean?" or "What's the meaning of (...)?" would be what you'd want to use.
From updated question
I thought only "what does _____ mean?" was grammatically correct but I heard a lot of Americans saying "what do you mean by _____?"
Are both of them correct? Are there any differences between those two?
If you ask "what do you mean by ____" then you are suggesting the person has said something you want them to explain. But "what does ____ mean" could be asked of someone whether they've said anything or not. You're just asking a question about the general meaning of something.
In usage, "What do you mean by that?!!?" can be a strong negative reaction...usually when someone has said something that the person feels was meant to be insulting even if it wasn't "obviously" so. So it's not really asking for clarification, because the speaker has already assumed it was meant in a bad way.
But it can also just be a polite phrase asking what someone meant.
Best Answer
Yes. In the standard American accent, Americans usually say do you something like dia sounds in Italian.
But the i sound would be shorter and softer than the Italian i sound.
Native English speakers and others with a basic sense of English spelling and pronunciation would likely use d'ya or similar to convey the kind of sound we can guess you have perceived.
An expert could provide a great deal of technical information, but that would seemingly be more useful in a different forum and/or in response to a question differently styled.