Complex sentence: Jonah and his friends spend the majority of their free time breakdancing in the school's amphitheater, which adds tension to a rivalary Jonah has with a year 7 breakdancer called Kieran.
Split into simpler sentences: Jonah and his friends spend the majority of their free time breakdancing in the school's amphitheater. This adds tension to a rivalary Jonah has with a year 7 breakdancer called Kieran.