Hello Nitay
The binding table is built by the DHCPv6 feature itself. The DHCPv6 Guard feature prevents the binding table from registering DHCPv6 replies and advertisements from rogue DHCPv6 servers. So DHCPv6 Guard protects the binding table from being populated by an non-endorsed source.
This protected binding table is then used by IPv6 Source Guard to filter inbound traffic on L2 switch ports that are not in the IPv6 binding table. More info on the IPv6 Source Guard feature can be found at the following link.
I hope this has been helpful!
Laz