First, it says, "Prove Yourself." This means you should show what you can do, not to others, but to yourself. It's like when you set a goal, and you work hard to achieve it. You're not doing it to impress anyone else, but to prove to yourself that you have the ability and determination to succeed.
Now, onto the second part, "To Yourself." This emphasizes that the most important person to impress and believe in is YOU. It's like being your own biggest cheerleader. When you achieve something and prove it to yourself, you build self-confidence and self-worth.
In simple words, this quote encourages self-motivation and self-confidence. It's about setting personal goals, working hard to achieve them, and in the end, feeling proud of what you've accomplished, not for others, but for your own self-belief and growth.