This is the 4986th most frequent Russian word.
курьеров
"Couriers."
The word 'курьеров' in this sentence is used in the accusative plural form to indicate the direct objects of the verb 'наняли' (hired). It refers to the individuals performing the role of couriers.
Мы наняли курьеров для доставки документов.
We hired couriers for document delivery.
Here, 'курьеров' is in the genitive plural form, used to describe the entity associated with the position ('должность'). It emphasizes the responsibility and punctuality expected of persons in this role.
Должность курьеров требует ответственности и пунктуальности.
The position of couriers requires responsibility and punctuality.
In this context, 'курьеров' is in the genitive plural form again, but this time it is used as part of a negative sentence implying the scarcity of skilled couriers.