This is the 2179th most frequent Russian word.
волонтеров
The Russian word "волонтеров" means "volunteers" in English.
In this sentence, "волонтеров" is the genitive plural form of the noun "волонтер", used to indicate possession or quantity ('the number of volunteers').
Волонтеров в нашем городе становится больше с каждым годом.
The number of volunteers in our city increases every year.
Here, "волонтеров" is in the accusative plural form of the noun "волонтер", indicating the direct object of the action ('invite volunteers').
Мы приглашаем волонтеров участвовать в благотворительных мероприятиях.
We invite volunteers to participate in charity events.
In this example, "волонтеров" is used in the genitive plural sense, showing a relationship of possession ('work of volunteers').