Overall meaning : Allah Almighty addresses all mankind, saying: People, it is you who stand in need of Allah, but Allah is self-sufficient and ever praised. If He wills, He can take you away and replace you with some new creation. This is no impossible thing for Allah due to His perfect power.
No person, who is already burdened with his own sins, will bear another’s burden; for every person will be repaid only according to his own actions. If someone who is weighed down should call upon others for help to bear his load, none of it will be carried by anyone, not even by a close relative!
You, Muhammad, can only warn those who fear their Lord though they cannot see Him and duly perform their prayers, as Allah commands. Only these can truly heed your warnings. Whoever purifies himself does so for his own benefit, and to Allah will everyone be returned to be repaid according to his actions.