hello tammy sorry for the inconvenience caused to you
dictate in word comes with office 365 subscription ..it seems you have already office 365 subscription->https://support.office.com/en-us/article/dictat...
for excel you need to use windows 10 speech re-recognition
go to control panel
easy of access
speech recognition
set up speech recognition if not set up
after that when ever your are in excel press win+cltr+s that would toggle speech recognition
and now you can convert speech to text
tips ->
->The more time you spend working on calibrating the microphone beyond the minimum requirements, the more effectively the software will recognize your voice commands. It's worth taking the extra time to eliminate later frustration.
windows speech recognition do evolve with your pronunciation with time
i would also like you to see if this feature is available in excel if not follow above steps ->https://support.office.com/en-us/article/dictat...
if your problem still persist please do reply