Perspectives help you drill-down test results for further analysis from business perspective. You can define custom criterion by setting up appropriate taxonomy on Scenarios and Test cases. For example, when you see a set of pass/fail test cases, you might want to know the breakdown of such failures based on Requirement ID or Priority or Line of Business.
When applied, you can filter a based on Perspective, across hundreds of tests cases in the report. This helps in quickly analyzing pass/fail tests with respect to a business parameters and make an informed Go/No-Go decision.
Perspectives are enabled in the report by using Custom Fields applied at Scenario or Test Case level. You can define custom fields in the project configuration and assign to Scenario and Test Case modules. For each Custom Field (Perspective), you can set multiple dimensions through a list of values. For example, you can set "High", "Medium" and "Low" dimensions for a perspective called "Priority". Click here for details. All the custom fields of type List, Multi-select or User List are picked up as dimensions for Perspectives.
When you are navigating in a test report, you can click on any of the segments in Perspectives graph and the test case list is filtered based on that segment. For example, picture below shows filtering applied on failed test cases for "SF Cloud = Marketing Cloud". To remove the filter, click on the same segment bar one more time.