In plain words
Heated and drawn out in the bright fire of knowledge, through hearing the teaching and the practices after it, the individual loses every impurity and, like gold without a flaw, becomes stainless and shines as itself.
Word for word
When refined in the radiant fire of knowledge through hearing [the teaching] and the subsequent disciplines, the individual, with all impurities gone, becomes stainless like flawless gold and shines as oneself.