"היום יום רביעי."
Translation:Today is Wednesday.
Can it also be 'יום ד'', because I set the language of my phone in hebrew and that is how it is on my phone
Yes in Hebrew you can say the names of the days like that too.
יום א', יום ב', יום ג', יום ד', יום ה', יום ו', יום שבת
(Saturday stays without a letter usually)
Okay. I know this question isn't to this sentence but I often saw words with " . Are that short versions of words?
It's called Gershayim (and the one ' is Geresh) it is used for acronyms.
For example: USA = ארצות הברית = ארה"ב
As you see it sometimes with more than initial letter.
Actually, it is not all that uncommon in spoken English to use what linguists call a "left-dislocation" in certain contexts. They actually serve special linguistic functions that you might not learn about in at least some English "grammar" classes. However, since "left-dislocations" or "pre-clausal dislocations" are much more common in Hebrew (sometimes for different reasons than English) and the above Hebrew sentence doesn't even use one, it's usually more accurate to default to "Today is Wednesday".
I posted more about "left-dislocations" in the following comment thread (if you're interested): https://www.duolingo.com/comment/16827893