This is the 264th most frequent Russian word.
пво
PVO (ПВО) stands for "Air Defense" (Protivovozdushnaya Oborona).
Here, 'ПВО' is used as a noun, an abbreviation, meaning 'противовоздушная оборона' (air defense).
ПВО отвечает за защиту воздушного пространства.
The air defense is responsible for the protection of airspace.
In this sentence, 'ПВО' refers to the military system or operations related to air defense.
Учения ПВО проводятся ежегодно для повышения боеготовности.
Air defense exercises are conducted annually to enhance combat readiness.
'ПВО' in this context refers to the technological and strategic implementation of air defense.