Overall meaning : We have created every single human being and We fully know the good and evil promptings of his innermost self; We are closer to him than even his jugular vein when the two angels set to record everything he says or does, one on his right and one on his left. No word does a person utter without it is being noted down by an ever-present vigilant angel.
The agony of death brings with it the truth that comes after death in terms of reward or punishment. This is the very death that you, man, tried to evade in the world! The Angel will sound the Trumpet on Judgement Day and all the dead will be raised. This is the day on which Allah has threatened to punish the unbelievers and evil wrongdoers! Every person will come forward, attended by an angel to drive him on before Allah and another angel to bear witness to his actions.
You were totally heedless, man, of this day in the life of the world. Now We have removed your veil, and so your sight is so sharp today that you can clearly perceive what you used to deny in the world.