The Dashboard menu is where you can find a brief overview of the notifications that have been sent out for the last 28 days. Displaying two charts that show when and how many messages were sent out by kind. It also allows you to dig down into the separate types of notifications that were sent out by clicking on the different notification methods that are listed in the table located at the bottom. They include the following; email, SMS, voice, and messenger. 

How do I hide/show one of the notification types in the charts?

To hide/show one of the notification types in either of the charts, click on the notification type directly under the chart that you would like to either hide/view on it.