This is where you create an execution, run it and then analyze and compare results. [All Executions] lists all the possible executions that were created and can be managed while clicking on Execution name links or New Execution button brings ‘Execution’ screen to run the tests.
The recommended way of creating Execution is 1 per execution cycle and then lock it for historical results. A good example of that would be creating execution for Smoke Test against a specific build, run it and then lock it. After the new build comes in, you create a new Smoke Test execution for that new build, run that and lock it as well. That way you’ll have two historical executions which you can then use ‘Aggregate’ report button to see their historical pass/fail rate for all test cases inside them.