You use the same verb for both, at least in the two meanings you are probably thinking of.
Polish has the following (the first verb in pair is imperfective, the second perfective):
mówić/powiedzieć – to say something, to tell something short
mówić/– – to speak a language
przemawiać/przemówić - to speak, to give a speech
opowiadać/opowiedzieć - to tell a story, to describe an event
rozmawiać/porozmawiać – to speak with someone, to converse
EDIT: since speaking a language is not an action that can be used in perfective sense, I fixed my list
That would be "Ona powiedziała dobranoc".
That comes from "powiedzieć", a perfective verb, which means that she said it 'succesfully'. From imperfective "mówić" you'd have "mówiła", but that would either mean that she said it on several occasions, or that she was... interrupted while saying it (didn't finish)?
Yes, I think "says goodnight" makes sense and is common in, at least, American English. "Wish goodnight" also makes sense, I think, but it's less common.
Also, I think these two phrases have different meanings, even though saying goodnight usually involves wishing goodnight (unless you're acting fake), and wishing it usually involves saying it.
"Saying..." puts the emphasis on the act of speaking the words, but "wishing..." refers more to the whole general act of extending your good will.
In English, "she says good night" and "she wishes him good night" is pretty much interchangeable, right? This is not the case in Polish, so this sentence is not valid, I believe. "Dobranoc" should be in quotes and the meaning is not the same as in "she wishes good night".
You wouldn't translate "say hello to..." as "powiedz cześć..."
Just wanted to point it out, because it may be confusing to English speakers.
"She wishes goodnight" is not good English. My ear, at least, demands a person to whom it is wished: "She wishes him goodnight", etc.
I'd also disagree with the claim that we don't 'say' goodnight. We do. It's by far the most common and natural form, and works without the 'him' or whatever. 'Wishing' good is rather oldfashioned.
"mówi" and "muwi" (if it was a word) would be pronounced the same way: "muvi" in English script.
"ó" and "u" are the same sound, it's only a matter of ortography. Mostly such differences are coming from the fact that words were pronounced differently a few centuries ago, but some sounds have come to sound the same now.
For example "morze" (the sea) and "może" (maybe) are pronounced the very same way nowadays.
i can't write it down by memory but i can write other polish words like ''tak'' and ''nie'' which means yes and no or''kogut '' and ''pies'' which means chicken and dog and anyway i know half the language .polish is so simple to learn I only started to lean polish like 1 month ago !!!!!!!!!!!!