Plain English Meaning
When a wing makes lift, it pulls air downward behind it. That downward-moving air tilts the oncoming airflow slightly downward too, so the wing meets the air at a less favorable angle than it would otherwise. The extra tilt added by this downward airflow is called induced AOA. Near the ground, that downward airflow is partly blocked, so induced AOA shrinks and the wing produces lift more efficiently.
Full Definition
The additional angle of attack created by the downward component of the relative wind (downwash) produced when a wing generates lift. Induced AOA is added to the geometric angle of attack to give the effective angle of attack the wing actually experiences. It is closely tied to induced drag and is reduced when the airplane is in ground effect, because the ground interferes with the formation of wingtip vortices and downwash.