Overall meaning :
This great surah opens with the ‘disconnected letters’ to establish the miraculous nature of the Qur’an, which conclusively prove the Arabs’ total inability to challenge the Qur’an by producing something like it, even though it is composed of the very Arabic letters they speak!
This Qur’an was undoubtedly revealed by Allah Almighty. It is a guidance for the righteous who believe in the unseen, duly perform the prescribed prayers, spend out of the good things He has provided for them, firmly believe in the Qur’an and all the revealed books Allah Almighty previously revealed, firmly believe in the ultimate resurrection and gathering, reward and punishment, the final judgement and the balance of deeds, among other things which Allah Almighty has prepared for people on the Day of Resurrection. Allah Almighty then states that these righteous people with the abovementioned characteristics are upon light, absolute proof and true guidance from their Lord and that it is they alone who will surely be saved and successful.