"And indeed, every time I invited them that You may forgive them" means: every time I invited them to repent from shirk (polytheism) and believe so that You may forgive them, they refused. "They put their fingers in their ears" as they turned away, loathing that. "And covered themselves with their garments" means: they covered their heads so that they would not hear my call.
﴿وَإِنِّي كُلَّمَا دَعَوْتُهُمْ لِتَغْفِرَ لَهُمْ﴾ أَيْ: كُلَمَّا دَعَوْتُهُمْ أَنْ يَتُوبُوا مِنَ الشِّرْكِ وَيُؤْمِنُوا فَتَغْفِرَ لَهُمْ، أبَوا ﴿جَعَلُوا أَصَابِعَهُمْ فِي آذَانِهِمْ﴾ يتولَّون وَيَكْرَهُونَ ذَلِكَ. ﴿وَاسْتَغْشَوْا ثِيَابَهُمْ﴾ غَطَّوْا رُءُوسَهُمْ؛ لِكَيْ لَا يَسْمَعُوا دُعَائِي