Jason Thomas has a great introduction to PowerApps:
you will be able to pass context aware data to a PowerApps app which updates in real time as you make changes to your report. Now, your users can derive business insights and take actions from right within their Power BI reports and dashboards. No need to switch tabs to open the separate apps, copy paste data from one window to another or worry about fat fingering the wrong customer id or invoice amount.
If you think about it, this is a game changer – you finally have a BI tool that allows you to collaborate and take actions right within the report. How many times have you looked at a report, found out an insight and wished that you could send an email to the account manager, only to forget later? Well, now you don’t have to worry about that, as I am going to show you an example of how we can collaborate by adding comments within the report (not just comments, but context aware comments, based on what you are selecting) as well as show how to send emails (to the appropriate people based on your selection).
This is an interesting concept and Jason has a detailed overview of it.