This is the 3525th most frequent Russian word.
резервных
"Reserve" or "backup" (adjective, genitive plural form).
The word 'резервных' is used in the context of describing 'brigades' as being in reserve or spare, highlighting their role as backup entities.
Резервных бригад надо подготовить к критическим ситуациям.
Reserve teams must be prepared for critical situations.
Here, 'резервных' modifies 'funds' to indicate that these funds are kept in reserve or as a backup to handle unexpected situations.
Наличие резервных средств укрепляет безопасность компании.
The presence of reserve funds strengthens the company's security.
In this usage, 'резервных' describes 'servers,' specifying that these servers serve as reserve or backup systems for data storage.