Imagine a situation where you are on a page and you have dropped a bounded task flow A as a region on this page. Now, from inside TF A you call another bounded task flow TF B which in turns calling a third bounded TF C. So, finally you are in task flow TF C.
Here, there are situations when you may need to navigate directly to TF-A rather to TF-B. So, in this case a task flow return activity will not help as it will only navigate you to the taskflow TF-B.
So, to go to TF-A you can drop a parent Action activity from component pallet on the task flow diagram of TF-C. In the properties define the parent outcome as some string value.
Now in the TF-B drop a task flow return activity and have a control flow navigation from your view activity to the task flow return activity. Give the name to this rule same as the parent outcome name you provided in TF-C.
That's it. Now, when you will will navigate from TF-C the flow will directly navigate to TF-A and skipping the TF-B.