In real senario ,When will there be necessity of using Forwarding (Layer2) virtual server.

I understand that when we create this virtual server , it uses any of nodel ip as the virtual ip address. COuld you clarify me on the below points.

 

• In real senario ,When will there be necessity of using Forwarding (Layer2) virtual server.
• ALso there is a note that we need to create a VLAN group that includes the VLAN in which the node resides, assigning a self-IP address to the VLAN group, and disabling the virtual server on the relevant VLAN . Where do we do these configurations in GUI . I dont see the option?