"And by those that separate [the truth from falsehood] separating," meaning: the angels who descend with revelation and separate between disbelief and belief, and between the lawful and the prohibited.
﴿فالفارقات فرقا﴾ يَعْنِي: الْمَلائِكَةَ تَنْزِلُ بِالْوَحْيِ فَتَفْرِقُ بَيْنَ الْكُفْرِ وَالإِيمَانِ، وَبَيْنَ الْحَلالِ وَالْحرَام