Your Activity Feed can be accessed by clicking the bell icon; the red dot will appear to show new notifications.
Items that are "unread" will also be marked with the red dot (see below), to show these have been seen or actioned you can click 'Mark as read' to clear.
If you have online booking enabled, new appointments will appear alongside the blue, globe icon
Replies to text reminders confirming appointments will use a green icon:
Replies to text reminders with an unclear response (anything other than "Y") will use a yellow icon:
Replies to text reminders cancelling appointments will use a red icon: