If you are added to a task by a teammate, or if someone comments on a task in which you're added, you will receive a notification (bell 🔔 - top right! 😊). This way you always stay up to date.
You can mark one, several or all notifications as read or "clean" the overview by deleting all notifications.
The notification feature is constantly being expanded. Next will be @mentions in comments, changes to tasks you are involved in and much more.