Complex sentence: In this light novel, 2.3 million students have esper ability, classified from level 0 to level 5: level 0 is no ability and level 5 is the most powerful and dangerous.
Split into simpler sentences: In this light novel, live 2.3 millions student with esper ability and divided into a category of level 0 to level 5. Level 0 has no ability and Level 5 is the most powerful and dangerous.