Hyper-V replica is a built-in feature of a Hyper-V role which is used to asynchronously replicate a selected virtual machine at a primary site to a designated replicated site.
It is a complete disaster recovery solution and it is easy to deploy. There are many replica configurations. In a simple configuration, you have one host server acting as a replica server and the other host acting as a replica client. The client pushes data to the server which maintains the replicas.
When you have a failover cluster of many servers, a replica site is logically represented by a replica broker. The process in the failover cluster replicates the VM in a secondary site to a replica broker which places the VM on failover cluster in associated primary site accordingly.