﴿ يَٰٓأَيُّهَا ٱلنَّبِىُّ إِنَّآ أَرْسَلْنَٰكَ شَٰهِدًۭا وَمُبَشِّرًۭا وَنَذِيرًۭا ﴾

“[And as for thee,] O Prophet - behold, We have sent thee as a witness [to the truth], and as a herald of glad tidings and a warner,”

(O Prophet!) He means Muhammad (pbuh) (Lo! We have sent thee as a witness) that you have conveyed the message to your nation (and a bringer of good tidings) i.e. Paradise to whoever believes in Allah (and a warner) against the Fire for those who disbelieve in Him.