This book a primer, which just means this is an introduction, a basic book to help you see how valuable you are and to assist you in becoming the best you can be. It's written for a middle school and high school audience and parents.
You have value. It's not value you earn. Your worth is intrinsic. It's in you, and no one can take it away from you.
You are born with this innate characteristic. You are unique and rare. Because of this, you have great value. If you "be the best you can be," then you can achieve your dreams, and the world will be a better place!
It's not about the group you belong to. It's not about the circumstances in your life. There will always be challenges, people who do bad things, adversity, betrayal, and suffering.
But you, as a strong individual, have the power within you to overcome these adversities. If you change the thoughts you think about yourself, work harder than everyone else, never give up, and take responsibility for yourself, you can accomplish your goals.