﴿ وَمَآ أَدْرَىٰكَ مَا ٱلْحَآقَّةُ ﴾

“And what could make thee conceive what that laying-bare of the truth will be?”

And how would you know what the Reality is? repeated as an extra emphasis of its enormity; the first mā of the previous verse is the subject the second one its predicate; the second mā and its predicate also function as the second direct object of the verb ‘knowing’.