This is the 1036th most frequent Polish word.
toruniu
"Toruniu" is the locative case of "Toruń," meaning "in Toruń" or "to Toruń," a city in Poland.
The word 'Toruniu' is the locative case of 'Toruń', used here because the sentence implies the location where the subject is.
Jestem teraz w Toruniu.
I am currently in Toruń.
The word 'Toruniu' is used in the context of discussion, which requires the locative case in Polish.
Mówiliśmy o Toruniu podczas lekcji historii.
We talked about Toruń during the history lesson.
The locative 'Toruniu' denotes the place where the future event is to occur.