Hello Hussein
This is essentially a change in semantics. In OSPFv2 we speak about networks. The destination network, the networks that are advertised. A network is expressed as, for example, 10.56.3.0/24. This is a destination or advertise network as far as OSPFv2 is concerned.
IN OSPFv3, the term that is used is link. This means that 2001:AB::0/64 found in the routing table for example is called a link in the context of OSPFv3.
The command to implement OSPFv3 on an interface is the following:
ipv6 ospf process-id area area-id [instance instance-id]
You can input this command several times with a different instance-id in each case and have the same interface (and subsequently its link) participate in multiple instances of OSPFv3.
I hope this has been helpful!
Laz