Say, [O Muhammad], "O mankind, indeed I am the Messenger of Allah (7:158)

﴿قُلْ يَا أَيُّهَا النَّاسُ إِنِّي رَسُولُ اللَّهِ إِلَيْكُمْ جَمِيعًا الَّذِي لَهُ مُلْكُ السَّمَاوَاتِ وَالْأَرْضِ ۖ لَا إِلَٰهَ إِلَّا هُوَ يُحْيِي وَيُمِيتُ ۖ فَآمِنُوا بِاللَّهِ وَرَسُولِهِ النَّبِيِّ الْأُمِّيِّ الَّذِي يُؤْمِنُ بِاللَّهِ وَكَلِمَاتِهِ وَاتَّبِعُوهُ لَعَلَّكُمْ تَهْتَدُونَ﴾
[ الأعراف: 158]

7:158 Say, [O Muhammad], "O mankind, indeed I am the Messenger of Allah to you all, [from Him] to whom belongs the dominion of the heavens and the earth. There is no deity except Him; He gives life and causes death." So believe in Allah and His Messenger, the unlettered prophet, who believes in Allah and His words, and follow him that you may be guided.

Allah tells the Prophet ( peace be upon him ) to inform people that he is the messenger of Allah to them all, both Arabs and non-Arabs.
Allah alone controls the heavens and the earth.
There is nothing worthy of worship other than Him, glory be to Him.
He brings the dead to life, and causes what is alive to die.
People should have faith in Allah and in Muhammad ( peace be upon him ), the Prophet, His Messenger, who cannot read or write, and who came only with what His Lord revealed to him, in order to guide them to what is good for them in this world and in the Afterlife.

Say (O Muhammad SAW): "O mankind! Verily, I am sent to you all as the Messenger of Allah - to Whom belongs the dominion of the heavens and the earth. La ilaha illa Huwa (none has the right to be worshipped but He); It is He Who gives life and causes death. So believe in Allah and His Messenger (Muhammad SAW), the Prophet who can neither read nor write (i.e. Muhammad SAW) who believes in Allah and His Words [(this Quran), the Taurat (Torah) and the Injeel (Gospel) and also Allah's Word: "Be!" - and he was, i.e. 'Iesa (Jesus) son of Maryam (Mary)], and follow him so that you may be guided."

phonetic Transliteration

Qul ya ayyuha alnnasu innee rasoolu Allahi ilaykum jameeAAan allathee lahu mulku alssamawati waalardi la ilaha illa huwa yuhyee wayumeetu faaminoo biAllahi warasoolihi alnnabiyyi alommiyyi allathee yuminu biAllahi wakalimatihi waittabiAAoohu laAAallakum tahtadoona

Abdullah Yusuf Ali - Translation

Say: "O men! I am sent unto you all, as the Messenger of Allah, to Whom belongeth the dominion of the heavens and the earth: there is no god but He: it is He That giveth both life and death. So believe in Allah and His Messenger, the Unlettered Prophet, who believeth in Allah and His words: follow him that (so) ye may be guided."

Safi-ur-Rahman al-Mubarakpuri

Say: "O mankind! Verily, I am sent to you all as the Messenger of Allah -- to Whom belongs the dominion of the heavens and the earth. None has the right to be worshipped but He. It is He Who gives life and causes death. So believe in Allah and His Messenger, the Prophet who can neither read nor write, who believes in Allah and His Words, and follow him so that you may be guided."

Page 170 English transliteration