You've enabled RSS feeds for Announcements, News and/or Events for your groups. Academic, Athletic, Advisory, Activity or Community, but you cannot see where the feeds are available.
The feeds will be available on the Browse Groups and My Groups page. To navigate here, go to Groups > View More > and select the Browse Groups Tab. You can also navigate here if you go to Classes > View Other Classes.
You can then search for the group you would like to subscribe to and click the RSS icon to the right of the group. This will expose the feed URLs for you to subscribe to.