When backing up NAS file shares, it's essential to ensure that more than one copy of the data exists to adhere to best practices for data protection, often referred to as the 3-2-1 Rule (3 total copies of your data, 2 of which are local but on different devices, and at least 1 copy offsite).
Implementing a secondary copy of the data provides this additional layer of redundancy. In Veeam, this can be achieved by creating backup copy jobs, which ensure that there is a secondary copy of the data, possibly stored in a different location. This is not to be confused with the simple use of backup repositories, which are storage locations for primary backups, or with cache/archive repositories which serve different purposes in the backup process.