Overall meaning :
The Almighty says: Do those who deny Our revelations and signs see that We have made the night dark so that they may rest in it from toil, and that We have made the day bright so that they may disperse freely on earth in search of their livelihoods? Surely in the creation of the night and the day and their differences there are signs for those who believe in Allah.
Mention to the people, Muhammad, the day when the Trumpet will be blown, and all those in the heavens and the earth will be terrified, except for those whom Allah wills to spare, and all of them will come to Him utterly humbled. And you will see the mountains, thinking them to be firmly fixed, but in reality they will moving along just like clouds. Such is the handiwork of Allah, who has perfected everything. He surely has full knowledge of what you do, and He will repay you according to your actions.