What does the badge on the application icon mean?
The badge on the application icon indicates how many days have passed since your last yoga or meditation session.
If you don't like to be reminded how many days have passed since your last session, you can disable this feature. You tap the settings button (bottom right) on the main view to bring up Samsara's settings.
Scroll to the section Badge and toggle the switch on the right to enable or disable the badge number on Samsara's application icon.