Hello, Nitin
When you create a rule, you can select a specific user OR group (ex: Data Insight Rule Approver) as approver and click on 'Submit for Approval' button at the bottom to send the rule to approver.
Once you send the rule for approval. the rule status changes to 'Submitted' state from 'Editing' state. You can see this status on the main rules page.
In order to approve rules, you can go to 'My Worklist' tab, and the rule will appear there if the rule is assigned to you. If the rule is assigned to a group, you can view that rule by unchecking checkbox 'Show Only My Worklist' option. Approver can approve / reject rules from there.
Hope the above info helps. BTW I am using IS 4.2, the process could be different in earlier versions of IS
Thanks