Hi Dinesh
Often Peer Groups are used when you have a lot of bgp peers with the same
update policies.
Like the same outbound route maps, distribute lists, filter lists, update source, and so on.
Neighbors with the same update policies can be grouped into peer groups to simplify configuration. Important also is to make updating more efficient. When you have many peers, this approach is highly recommended.
For konfig sample i would recommend you the config guides from cisco.
Hope that helps
Roger