Word by Word Analysis

أَفَمَن شَرَحَ ٱللَّهُ صَدْرَهُۥ لِلْإِسْلَـٰمِ فَهُوَ عَلَىٰ نُورٍ مِّن رَّبِّهِۦ ۚ فَوَيْلٌ لِّلْقَـٰسِيَةِ قُلُوبُهُم مِّن ذِكْرِ ٱللَّهِ ۚ أُو۟لَـٰٓئِكَ فِى ضَلَـٰلٍ مُّبِينٍ 22

So is one whose breast Allāh has expanded to [accept] Islām and he is upon [i.e., guided by] a light from his Lord [like one whose heart rejects it]? Then woe to those whose hearts are hardened against the remembrance of Allāh. Those are in manifest error.