The Supplication`s name is sayyidal-astagfar. It is a great supplication to be forgiven. If you memorize it and read it after every salat, you will in sha Allah be forgiven your faults. If you read it twice a day, one time in the morning and one time before you go to sleep, if you die, you will in sha Allah enter Paradise. If you read the supplication every day, you would also want to do more of ibadaah (praying to Allah). It is also very great to calm oneself and be in peace. I have used some time and memorized it, I hope each and every reading this would take out some time and try to memorize it and read it frequently in sha Allah ameen. May Allah forgive us our shortcomings and give us glad tidings of Paradise and a blissful life before and in the hereafter. Ameen summa ameen.