You've been using static since your first public static void main. Now that you understand objects, you can see what static means in context.
A static field belongs to the class, not to any object. If you write static int count; inside Car, there is only copy of count shared by all Car objects. A static method works the same way. It belongs to the class and cannot access instance fields or this.
Car.count = 5;
You call it on the class name, not on an object. Use static for data or behavior that doesn't depend on a specific object's state.