This is the 281st most frequent Russian word.
войск
"Войск" is the genitive plural form of "войско," meaning "troops" or "forces."
The word "войск" here is in the genitive plural form and refers to military units (troops) managed by a commander.
Командир войск разработал план обороны.
The commander of the troops developed a defense plan.
In this sentence, "войск" is used in the genitive plural form, indicating possession or relation to troop movements.
Передвижение войск было замечено разведкой.
The movement of troops was detected by reconnaissance.
Here, "войск" is again in the genitive plural form, signifying association with the allied forces.