This is the 15043rd most frequent Russian word.
пожарная
"Firefighter" or "related to fire service."
Here, 'пожарная' is used as an adjective meaning 'fire', describing the noun 'машина' (truck).
Пожарная машина быстро подъехала к месту происшествия.
The fire truck quickly approached the scene of the incident.
In this sentence, 'пожарная' is a noun and refers to a female firefighter.
Работая пожарной, она спасла множество жизней.
While working as a firefighter, she saved many lives.
Here, 'пожарная' is part of the compound noun 'пожарная тревога', meaning 'fire alarm', again serving as an adjective.