@Aftab 

I can think of 3 ways.. it all depends what is the actual information that you need

• download flow data and there you can see all the numbers for the flow
• if you don’t have any specific splits before the first email.. the first email can tell you how many people got it or how many skipped it for specific reason.. and I guess all together is all the people who triggered this flow
• second option is to recreate the flow setup as a segment.. so if you want to see how many people triggered it and qualified to go through it create segment with definitions for the flow trigger and trigger filters and also include the flow filters of the flow.. and if you want to see all the people who started this flow (even those that got filtered out because of flow filters) create a segment just with flow trigger and trigger filters if you have them as the segment definitions