Don't plan on a job before you turn 16: an employer who hires you is fined 5000 CNY a month, and the ones willing to are knowingly breaking the law

In plain words

Finishing middle school usually happens at 15 or 16, right at this line. Under 16, an employer who hires you is breaking the law and is fined 5000 CNY a month for each child worker. So the employers who will take you are the ones who know it is illegal and do it anyway. If something goes wrong, medical bills and compensation can only be claimed from that employer, and if it refuses to pay or disappears, no one else covers it.