So why would you need translated subtitles when givng a PowerPoint presentation?
You are presenting an important PowerPoint presentation in English worldwide. Not all of the attendees are fluent in English. But there is an important point you want to make sure that everyone understands. So after ascertaining which language you would like PowerPoint to translate (for example Mandarin), you decide to get PowerPoint to transcribe your spoken English into simplified Chinese characters.
Alternatively, you may just want to display English subtitles. This would be handy for anyone who can't literally hear the presentation for any reason. Perhaps in a busy office or at home and doesn't have access to headphones.
There are any number of reasons as to why you would want to use captions in PowerPoint.
This five minute video will tell you how to access this super useful tool!
Use PowerPoint to Present in Multiple Lanuages
Enjoy!