Word by Word Analysis

أُو۟لَـٰٓئِكَ ٱلَّذِينَ ٱشْتَرَوُا۟ ٱلضَّلَـٰلَةَ بِٱلْهُدَىٰ فَمَا رَبِحَت تِّجَـٰرَتُهُمْ وَمَا كَانُوا۟ مُهْتَدِينَ 16

Those are the ones who have purchased error [in exchange] for guidance, so their transaction has brought no profit, nor were they guided.