To perform an Aerial combo you must collect 5 airborne Orb Essence by jumping through them all in one leap. The orbs look like two diamonds connected to each other and come in four colors.
Yellow: 100 points
Orange: 150 points
Pink: 250 points
Purple: 500 points
This can be done easily on the tutorial, on about the 3rd left that you take you will see a low wall that you must jump over to progress through the level. There is a perfect set of 5 Orbs in an arch over the wall. Collect them all in one jump and you will bag the achievement.
Just to be sure here is a pic with an arch of orbs in the bottom left.