I haven’t seen anyone using below report and command yet. Generally, this is an administrative job to ensure that traffic (Inbound /Outbound) of your Office 365 is healthy.
It gives you a view what is going on in your Office 365 tenant. Actually, when I first saw it, I didn’t understand it because there are many Event Types that we can’t understand unless we know the meanings of types.
Let’s give couple of examples
I would like to see Inbound traffic between 13/05 and 15/05
Get-MailTrafficReport -Direction Inbound -StartDate 05/13/2017 -EndDate 05/15/2017
If you would like to see Outbound traffic, run below
Get-MailTrafficReport -Direction Outbound -StartDate 05/13/2017 -EndDate 05/15/2017
Event types are actually little bit complicated, it would be better if you read Microsoft article about them.