This is the 17347th most frequent Polish word.
zapalenia
"Zapalenia" in English means "inflammations."
Here, 'zapalenie' is used as a medical condition, specifically an inflammation.
Mam zapalenie oskrzeli.
I have bronchitis.
Here, 'zapalenie' refers to the act of lighting something.
Zapalenie świec raczej nie było dobrym pomysłem.
Lighting the candles was probably not a good idea.
In this context, 'zapalenie' indicates the ignition or catching fire of an object.