You can tailor exactly what you want to hear about when you use Heelix. To check what you're being notified about (and to change it based on your own preferences), simply head to the Notification settings in the left hand nav bar on the web app.
From here, you can choose which type of notifications you want to hear based on the Spaces you are a part of. Simply hover over each of the options to see which one you would prefer:
You also have the option to choose specific users to follow or mute and to turn the weekly digest on or off: