Financial literacy for sure. Credits cards, loans, interest rates, compound interest for savings and pensions. Mortgages. Investments. Understanding the financial implications of marriage. Being clear on when debt is shared and when it isn't, implications of taking on debt for others etc. Protect them against being financially exploited.
Critical thinking. Being able to e.g. assess whether the job they'd love to do is compatible with the lifestyle they'd like to have, and adjusting accordingly. Whether that thing in the news is in any way reasonable. Whether the offer someone made you is reasonable or not.
Learning how to learn effectively, so that throughout their life they can acquire new knowledge and skills as they need them. Learning how to research anything they might need to know, and which sources to trust (not purely academic, life skills in all forms, holidays, financial info, new cars, recipes, DIY etc etc).
Self confidence. Knowing that they have value innately, and don't need to people please to feel wanted.
And relatedly, not to take things personally, because everyone is wrapped up in their own life and whatever behaviours you see, they're probably not about you.
Negotiation skills - almost everything in life is a negotiation between your wants and needs and the other person's wants and needs.
Positive psychology - tools and strategies to be and stay happy, resilient and thriving.
How to eat, sleep and exercise healthily and find ways that you love to do these - you only have one body, and when it stops being healthy, everything else becomes harder, so learn all the skills and habits to keep it as healthy as possible for as long as possible. Also basic medical care/first aid, meditation, etc for the same reasons.