Nearby ayahs help place verse 47:3 in sequence and meaning.
ٱلَّذِينَ كَفَرُوا۟ وَصَدُّوا۟ عَن سَبِيلِ ٱللَّهِ أَضَلَّ أَعْمَـٰلَهُمْ
Those who disbelieve and avert [people] from the way of Allah - He will waste their deeds.
وَٱلَّذِينَ ءَامَنُوا۟ وَعَمِلُوا۟ ٱلصَّـٰلِحَـٰتِ وَءَامَنُوا۟ بِمَا نُزِّلَ عَلَىٰ مُحَمَّدٍ وَهُوَ ٱلْحَقُّ مِن رَّبِّهِمْ ۙ كَفَّرَ عَنْهُمْ سَيِّـَٔاتِهِمْ وَأَصْلَحَ بَالَهُمْ
And those who believe and do righteous deeds and believe in what has been sent down upon Muhammad - and it is the truth from their Lord - He will remove from them their misdeeds and amend their condition.
فَإِذَا لَقِيتُمُ ٱلَّذِينَ كَفَرُوا۟ فَضَرْبَ ٱلرِّقَابِ حَتَّىٰٓ إِذَآ أَثْخَنتُمُوهُمْ فَشُدُّوا۟ ٱلْوَثَاقَ فَإِمَّا مَنًّۢا بَعْدُ وَإِمَّا فِدَآءً حَتَّىٰ تَضَعَ ٱلْحَرْبُ أَوْزَارَهَا ۚ ذَٰلِكَ وَلَوْ يَشَآءُ ٱللَّهُ لَٱنتَصَرَ مِنْهُمْ وَلَـٰكِن لِّيَبْلُوَا۟ بَعْضَكُم بِبَعْضٍ ۗ وَٱلَّذِينَ قُتِلُوا۟ فِى سَبِيلِ ٱللَّهِ فَلَن يُضِلَّ أَعْمَـٰلَهُمْ
So when you meet those who disbelieve [in battle], strike [their] necks until, when you have inflicted slaughter upon them, then secure their bonds, and either [confer] favor afterwards or ransom [them] until the war lays down its burdens. That [is the command]. And if Allah had willed, He could have taken vengeance upon them [Himself], but [He ordered armed struggle] to test some of you by means of others. And those who are killed in the cause of Allah - never will He waste their deeds.
سَيَهْدِيهِمْ وَيُصْلِحُ بَالَهُمْ
He will guide them and amend their condition