When Folktells offers to tell a story, it listens for voice confirmations using speech recognition. Instead of tapping a button, you can say 'yes' or 'no'.
Both iOS and Android support voice commands but when asking for permissions, they use different terminology.
On iOS 10+, you will be prompted to allow access to speech recognition. On iOS 12+ you will also be prompted to allow access to the microphone.
On Android, you will be prompted to allow Folktells to record audio.
If you choose to deny permission for these features, you can still use all the functionality of Folktells but voice input will be disabled. If you at first deny access and later change your mind, you can grant permissions in the device system settings for Folktells.