Notifications regarding all Jobs you Posted or Applied for will be found here. You can Toggle these notifications on and off by going to Profile > Settings > Notifications.
A Red number alert will appear on the Notifications Icon to make you aware of new messages. The blue notification dot within the page of alerts as noted below on the next picture means it is a new message. Once you tap or view the notification, the blue dot is gone, and the red number alert will decrease.
Notifications can be deleted by swiping from right to left, then choosing "Delete".
Tap on any Notification and it will be directed to the related Job.
You can also Clear Notifications by tapping on the Ellipsis to the top right. Here you will be able to Clear All Notifications, Get Help or Share the App.