It means that you entered Prestige mode. Prestige allows you to "restart" the game from the very beginning while keeping all the skills, gems, Ultimate parts and Ultimate banknotes/cash, and catsomization costumes. Your car, all your coins, and spare parts will be reset. This action is irreversible.

We understand how frustrating it might be to lose your cars but don’t worry, this is something all the players go through. Gaining as many prestige levels as you can is one of the goals of the game.

Leaving everything behind each time, you progress through the game, face stronger opponents and obtain better parts. There are now a lot of new exciting opportunities and a lot of fun in front of you. We hope you'll enjoy it!