"Se concentrer sur une chose et la faire vraiment, vraiment bien peut vous mener très loin"

Simplified Meaning:

When you dedicate all your attention and effort to doing one thing excellently, you can achieve great success. For instance, think about a professional athlete like a tennis player. They spend most of their time practicing tennis, working on their skills, and improving every tiny aspect of their game. Because they focus so much on this one sport, they become very good at it and can compete at the highest levels. Similarly, in your own life, if you choose one area, such as playing a musical instrument or mastering a subject in school, and put in a lot of effort to get good at it, you can become very successful in that area. This focused approach helps you build deep knowledge and skills, which can open many doors and opportunities. Instead of trying to do many things at once and being okay at them, getting really good at one thing can take you much further. This can lead to personal satisfaction, recognition from others, and possibly even a rewarding career.