To understand, to get it. Suddenly understanding a complex idea, getting the point of a joke, or grasping the reality of a situation.
То есть они реально не въехали, что раньше было можно, а теперь стало нельзя.
That is to say they really did not get it that you could in the past but now you can’t.
(Борис Акунин @ ЖЖ, 07/2013)
