Questions & Answers about Którego dziś mamy? — Dziś jest trzeci marca.
Literally, it is something like Which one do we have today? or, more fully, Which day of the month do we have today?
In natural English, the best translation is simply What’s today’s date?
This is an idiomatic Polish way to ask for the calendar date, so it does not match English word for word.
This is a very common learner question.
The form którego is usually understood as a shortened version of Którego dnia miesiąca dziś mamy? = Which day of the month is it today?
So którego refers to an implied dnia = day, which is in the genitive.
You may also hear Który dziś mamy?, which is also common in modern Polish. So do not be surprised if you meet both versions.
Mamy is the 1st person plural of mieć = to have.
Polish often uses mieć when talking about the date:
- Mamy trzeci marca.
Literally, that is We have the third of March.
English does not use have this way, but Polish does. It is just a normal idiomatic pattern. Polish can also use jest:
- Dziś jest trzeci marca.
So both mamy and jest can appear in date expressions.