This translation is too loose. The idea translates correctly, but it's a different sentence by structure.
Jakie masz marzenie? = What dreams do you have?
What is your dream? = Jake jest twoje marzenie?
Am I right, my Polish friends?
Almost right, but I think both versions are close enough.
"Almost", because there's no need to mix sg "marzenie" and pl "dreams", you could just ask "Jakie masz marzenia?" in plural.
And now there's a question of which sentence is more natural in its langugage. I can't speak for English, but my guess would be for "What is your dream?". And in Polish... I'd say 60/40 to "jakie masz marzenie?"
You can also ask "O czym marzysz?" = What do you dream about?, with 'dream' of course still not meaning anything about sleep.
"Marzenie" is something you want to happen, an aspiration. "Sen" (plural: "sny") is what you dream while sleeping (you sometimes say "marzenie senne"). "Sen" can also refer to the action/state of sleeping. E.g.
Moim marzeniem jest zostać pilotem. = My dream is to become a pilot.
Miałem dziwny sen. = I had a weird dream.
Zapadł w głęboki sen. = He fell into a deep sleep.
'sen' - a series of thoughts, visions, or feelings that happen during sleep 'marzenie' - something that you have wanted very much to do, be, or have for a long time
Yes, a dream to become a doctor in the future, not a dream you dream at night (which is "sen").
"Jakie są twoje marzenia", literally. Although it's quite okay as a sentence, I'd go for the version with 'have', anyway.
You're right, not necessarily but commonly. I'm a native English speaker. If someone is asking about what dream you want to follow, like becoming a singer or an artist, or something like that, then they'd say, "do you have a dream?" first, and then the follow-up would be "what dream (do you have)?" If you just ask this way by itself, out of context, then the context is what dream do you have when you sleep? --"I have a dream that I'm flying over the city," or something like that, usually the question implies a dream that repeats
I still don't understand why "what dream do you have?" is not correct.
I said 'What dream do you have? I think that translates the same but I expect I speak English in an archaic way!