Blizzard has released a short YouTube video giving a quick overview of the upcoming Dragonflight features!
Dragonflight Expansion Overview
World of Warcraft Dragonflight
Return to Azeroth
Explore the Dragon Isles
Play the New Class: Dracthyr Evoker
Customize Your Abilities
Not mentioned in the video is Professions though which are undergoing a massive rework in the expansion!