As a general rule, your employer must make sure your working conditions are safe
Your employer must give you all the training and information you need to do your job safely.
If you're under 18, your employer must make sure you have the necessary skills and experience to do your work. For example, your employer could refuse to give you factory work operating dangerous machinery if you don't have any experience in this area.
Some jobs also have a minimum age requirement. For example, you can't work in a bar if you're under 18.
Keep in mind that the law also has many other rules about the workplace, for example, rules on pay, overtime and breaks.
This article explains in a general way the law that applies in Quebec. This article is not a legal opinion or legal advice. To find out the specific rules for your situation, consult a lawyer or notary.