Soz means ardour, a burning for a person or a cause.
Faiz means goodness. As in, to good for others.
Now let's get into a little detail.
Surkh wala love would mean a deep love. If you still want to try a little more meaning, you can think of it as the colour of one's eyes as there is Soz, ardour, a burning for the person you love. And then there is faiz wala love, that is a love that thinks about the good of the person you love, and not just about yourself.
Thanks for the lovely lyrics to Anvita Dutt.
P.S. We see that Faiz in many places is written as 'victorious'. Here it should be worth a mention that this Faiz in Urdu comes from Persian instead which means 'Grace'.
Check All Lyrics, Meanings and Translations from Student of The Year HERE.