What do I enter onto the required fields when using the fetch of a certain app?

What do I enter onto the required fields when using the fetch of a certain app?

I am confused as to what to enter in the required field of the fetch action of certain apps. From my understanding, fetch action allows users to get additional information lacking from the trigger. I have tried to use this but each time I tried and placed the fetch name onto the ending app of the flow, it does not place any name at all but is instead blank. How should I go about this? The guide about using fetch did not explain properly and deeply how fetch actions work. 

I hope that someone or the Zoho team could help me on this, at least a deeper and detailed information about how to use fetch action would be awesome and a great help to me.