Bismillah
Allah (سبحانه وتعالى) says in Suratul Anbiya:
لَوْ يَعْلَمُ الَّذِينَ كَفَرُوا حِينَ لَا يَكُفُّونَ عَن وُجُوهِهِمُ النَّارَ وَلَا عَن ظُهُورِهِمْ وَلَا هُمْ يُنصَرُونَ
Translation: If only those who disbelieved knew when they will not be able to ward off the Fire from their faces, nor from their backs; and they will not be helped. [Surah Suratul Anbiya, verse 39]
The word for ward off is “yakuffoona”, “يَكُفُّونَ” and this is from the root word “ka-fa-fa” or “kaff” which means palm/hand. The disbelievers will not be able to put their hands out, avert or prevent themselves from the punishment. Imagine if something is coming towards your face, what is the first thing you would do? Cover and protect your face with your hands, right? The disbelievers will not be able to do this, they will not be able to avert or obstruct the fire from their faces. may Allah (سبحانه وتعالى) protect us from it, ameen. And Allah (سبحانه وتعالى) continues, “nor from their backs” وَلَا عَن ظُهُورِهِمْ Now if something came towards your face and you were not able to cover it your hands, what would you do then? Turn around and protect yourself with your back, right? The disbelievers will not even be able to do this when the fire comes to them, “and they will not be helped”. No one will be there for them. No helper or assistant to come and save them from the punishment.