There is no integrated backup in RHV Manager.
Use traditional backup methods to protect your virtual machines and hosts (e.g. backup agents for network based backups in individual virtual machines and RHEL hosts). However you can of course export virtual machines and templates onto the export domain (NFS).
Background: Export domains are temporary storage repositories that are used to copy and move images between data centers and RHV environments. They can be used to backup virtual machines. An export domain can be moved between data centers, however, it can only be active in one data center at a time. Support for export storage domains backed by storage on anything other than NFS is being deprecated - new export storage domains must be created on NFS storage.
Additionally a tool for backing up and restoring RHV Manager database and certificates is available.