Do not encourage him, but if he continues to seek for your help, first start with all the disadvantages of trading, there are real life cases of people that have lost millions to trading and regretted about it, you need to show him all these to let him know where to start and what to avoid.
A child may be eager to learn about trading at this age, unaware that trading is more than just making money. He is correct, but there is more to it. You must be cautious because, at this age, he will have no concept of losing money; all they care about is making money. To add to what you have said, it is important to understand the disadvantages of trading as well as the risks involved. Because the child does not have his or her own money, you must exercise caution to avoid losing your money.
Encourage him and teach him everything he needs to know about trading; a child at this age who is willing to learn trading will be a great Trader, successful Trader, and expert in the future, so just do what is necessary.