Learn Polish: Pociąg ma opóźnienie, teraz jest za kwadrans piąta. - The train has a delay, now it is a quarter to five.

When telling the current time with za (meaning 'to' the hour), the preposition only affects the minutes that follow it. In za kwadrans, the word kwadrans is in the Accusative case. The hour itself (piąta) stays in the Nominative case because the core sentence is simply 'It is five' (jest piąta).

Does za kwadrans literally mean 'a quarter to'?

It literally translates to 'in a quarter'. Polish expresses 'a quarter to five' by saying 'in a quarter, it is five'. The preposition za takes the Accusative case here, but since kwadrans (a quarter of an hour) is a masculine inanimate noun, its Accusative form looks identical to its dictionary form.

Why does the Polish sentence say ma opóźnienie instead of 'is delayed'?

In Polish, it is much more natural to say that a vehicle 'has a delay' (ma opóźnienie) rather than using an adjective like 'delayed'. Opóźnienie is a neuter noun acting as the direct object of the verb ma, so it is in the Accusative case.

Can I say piętnaście minut instead of kwadrans?

Yes, you can absolutely say za piętnaście piąta. Kwadrans is just a very common, built-in word for a 15-minute period, similar to saying 'a quarter' in English.