Overall meaning : You, Muhammad, who are covered up with your clothes in fear! Arise and warn the unbelieving idolaters of Allah’s punishment if they do not declare His oneness and worship Him alone; magnify your Lord and declare Him free from all imperfections; purify your garments from impurities, yourself from the stains of sin and your good deeds from doing them for other than Allah and from wrongdoing; keep away from idol worship; do not give something expecting more in return and patiently endure whatever harm you suffer for Allah’s sake.
When the Trumpet is sounded on Resurrection Day for people to be raised from their graves for judgement, that will surely be a very difficult day, not at all easy for the unbelievers.