This is the 750th most frequent Polish word.
żołnierze
"Żołnierze" means "soldiers" in English.
Here, 'żołnierze' is used as the subject of the sentence referring to a group of soldiers performing an action.
Żołnierze przemaszerowali przez miasto.
The soldiers marched through the town.
In this sentence, 'żołnierzach' is in the locative case, used after the preposition 'o' to denote the topic of the stories.
Mój dziadek opowiada historie o żołnierzach z czasów wojny.
My grandfather tells stories about soldiers from wartime.
Here, 'żołnierzy' is in the genitive case, used to describe a partitive relation with 'grupę' (a group).