﴿ أُو۟لَٰٓئِكَ هُمُ ٱلْكَٰفِرُونَ حَقًّۭا ۚ وَأَعْتَدْنَا لِلْكَٰفِرِينَ عَذَابًۭا مُّهِينًۭا ﴾

“it is they, they who are truly denying the truth: and for those who deny the truth We have readied shameful suffering.”

Those are the disbelievers truly haqqan is the verbal noun emphasising the content of what precedes it in the sentence; and We have prepared for the disbelievers a humiliating chastisement namely the chastisement of the Fire.