Each user will get notified of when you get a new lead or a message from an existing lead. Notifications will show on desktop and mobile. You can turn on and off the notification bell sound from your settings.
If you are on an active tab, then you will only see red dot notificaitons.
If you are on another tab, then you will get a normal desktop notificaiton alert. If you are not on desktop, but you are logged in on your mobile, you will get a notification there.