These lyrics totally explain and defend how asad is feeling at the moment. The feeling hat his heart is trying to speak for days on end that it longs for zoya, his love. Its been supressed for long but now its time for the heart to speak through the mouth of asad and to ears of zoya ( asads soniye ).
At first i wasnt fan of the song choice because i feel they could have picked something better and i still feel that way just a bit, but im happy with this song choice because it has so much significance to asads emotions atm. He is trying to tell zoya his feelings and the son is basically saying the same.
Another major significance of this song you guys: its the first song and dance we will have of AsYa that is NOT UNDER ANY FALSE PRETEXT! As much as i loved the other songs and dances, they were all either under a pressure or reason: bhol na halke (bhang) teri meri (bet) holi (had everyone not just asya) ishq hua (dream) etcc... So
Sun zara will hopefully be the FIRST SONG PURELY ASYA AN PURELY REAL AND UNDER NO PRETEXT !
Time to celebrate guys!