Questions & Answers about Nadchodzi zima.
Nadchodzi is a verb. It is the 3rd person singular present tense form of nadchodzić.
So literally, it means something like:
- is approaching
- is coming
- comes near
Because zima is singular, the verb is also singular: nadchodzi.
Because zima is the subject of the sentence.
In Nadchodzi zima, the thing that is approaching is winter, so zima stays in the nominative case, which is the dictionary form.
Compare:
- Zima nadchodzi. = Winter is coming.
- Nie lubię zimy. = I don't like winter.
Here zimy is not the subject, so the form changes.