정한X조슈아 (SEVENTEEN) '12 o'clock' Official Teaser 1

In the Korean comments

One top comment reads, in translation, “와..얼굴 무슨일..얼굴합 좋다” (Wow… what is going on with their faces… their faces work so well together). The key phrase is 얼굴합 (eolgulhap, facial combination): it praises how good the two performers look together, not their faces separately.

What the words mean

눈 호강 (nun hogang) literally means “luxury for the eyes.” In the comment “가장 이쁜 얼굴 둘이서.. 눈 호강한다야” (The two prettiest faces together… what a treat for the eyes), it is a casual, exaggerated way to call something exceptionally pleasurable to look at.