This is the 7440th most frequent Polish word.
konferencję
"Konferencję" in English means "conference."
Here, 'konferencję' is used in the accusative case to denote the object of participation.
Uczestniczyłem w konferencji naukowej.
I participated in a scientific conference.
'Konferencję' functions in the accusative case as the direct object of the sentence indicating what was organized.
Zorganizowali konferencję w hotelu.
They organized a conference in the hotel.
While not 'konferencję', contextually in the example sentence's explanation, 'konferencja' is placed in the locative case ('konferencji') to indicate the location of the action.