This is the 13152nd most frequent Polish word.
ogniowej
"Ogniowej" means "fire-related" or "of fire" in English.
Here, 'ogniowa' is used as an adjective describing 'linia' (line), related to fire or military operation involving fire.
Linia ogniowa była dobrze przygotowana.
The fire line was well prepared.
In this sentence, 'ogniowa' qualifies 'bariera' (barrier), referring to its function or relation to fire.
Bariera ogniowa powstrzymała przeciwnika.
The fire barrier stopped the opponent.
Here, 'ogniowa' describes 'strefa' (zone), indicating its association with fire or a situation involving fire.