Complex sentence: Jung Joon-young was a main MC and a guest for this concert and he sang "BakHa Candy" (박하사탕 YB Band) which was his second audition song of Superstar K4.
Split into simpler sentences: Jung Joon-young was a main MC and a guest for this concert. He sang "BakHa Candy" (박하사탕 YB Band) which was his second audition song of Superstar K4.