This is the 5271st most frequent Russian word.
огне
"Огне" is the prepositional case form of "огонь," meaning "fire" in English.
In this sentence, 'огне' is used in the instrumental case to denote the medium or source by which the action is performed.
Я зажёг свечу на огне.
I lit a candle on the flame.
Here, 'огне' is in the prepositional case, indicating the location where the action is taking place.
На огне горел старый стул.
An old chair was burning in the fire.
The phrase 'на открытом огне' uses 'огне' to specify the method or tool utilized in the action.