Press the icon in Argo’s top menu. If there’s a red badge on the notifications icon, that means you have new notifications.
Once you open notifications, all new notifications will have red dots next to them. These will disappear after you close notifications.
Direct message notifications do not appear in the notifications screen, instead you can read new messages by tapping on the Messages icon in Argo’s bottom menu. A red badge with the number of new messages will appear on the Messages icon when you have new messages.