This is the 11004th most frequent Polish word.
festynie
"Festynie" is the locative form of "festyn," meaning "festival" or "festivity" in English.
In this sentence, 'festynie' is used as a locative case ('na festynie') to specify the location of the action taking place, namely the festival.
Byłam na festynie w zeszły weekend.
I was at a festival last weekend.
Here, 'festynie' denotes the event at which the eating occurred, and it is part of the prepositional phrase 'na festynie'.
Zjadłem pyszną kiełbasę na festynie.
I ate a delicious sausage at the festival.
In this instance, 'festynie' refers to the festival as the setting of the activity, indicating where the balloons were distributed.