Absolutely nothing is "difficult to understand" about this scandal. Hillary set up an illegal email system to run her SoS and Clinton Foundation business free from any oversight. The two streams were intricately and illegally linked, as the inflow of money to her husband and her foundation influenced her actions as the Secretary of State. As a result of that jaw-droppingly criminal activity, the illegal email system facilitated her trafficking of classified information over non-secured channels, exposing that information to interception by our enemies.
There, that was easy to explain. The media uses the "difficult to explain" excuse to cover up their failure to cover the story for partisan political reasons.