Overall meaning : When the inevitable Day of Resurrection comes, no one will then deny its occurrence. It will abase some who will be cast into Hell and exalt others who will be admitted into Paradise.
On that day, the earth will be violently shaken, the mountains will be dashed into pieces and reduced to particles of dust scattered about and you, people, will be sorted out into three classes: The Companions of the Right Hand (How happy the Companions of the Right Hand will be!); and the Companions of the Left Hand (How miserable the Companions of the Left Hand will be!)