Overall meaning :
Almighty Allah states that those who disbelieve, avoid treading the path of truth and prevent others from treading it have indeed strayed far away from the right path.
He points out that He will never forgive those who have disbelieved and wronged themselves by rejecting faith, nor will He ever guide them to the right path leading to the bliss He has in store for the righteous. He will, instead, guide them to the path of falsehood leading to Hell, where they will abide forever. Surely that is easy enough for Him.
Then, addressing all mankind, He declares that His Messenger, Muhammad, may Allah bless him and grant him peace, has brought them the truth from Him, and He exhorts them to believe him, stating that doing so will be better for them both in this world and the next. If they refuse and deny him, He sternly warns, then Allah is self-sufficient and does not stand in need of them, for to Him belongs all that the heavens and the earth contain, and He is All-Knowing, All-Wise.