When I originally clipped this, I didn't know what 남자 meant, and didn't think to look it up.
#skzSubtitleTeam just put the transliteration (namja) in both the Korean and English subtitles. Seemed a little strange to me, but I didn't bother to look it up at the time.
남자 means man. #Felix was checking #LeeKnow out and feeling his muscles and appreciatively saying 'man' like all his higher brain functions had shut down.