understanding the cppreference definitions page

1. This is the incorrect use of the post type "code snippet." Read what it is, how and when to use that.

2. I'd use "Order-based initialization"
   Example that might replace line 8.

   // Order-based initialization
   Player s{1, 2, 3};

Now you would have an object Player with the initial values you wanted.

from : https://cppreference.com/cpp/language/definition

i don't understand what they mean by

"Declaration of a non-inline(since C++17) static data member inside a class definition:"

looking at the code there are definitions and declarations but i tried switching between the drafts and saw no difference

can someone please help understand this what are they trying to say ? i am new to c++ and english is not my first language

Classes and structures do not create any data storage until an instance if them is declared (e.g. S s1, s2, s3). At that time, non-static data members come into existence.
A static class/struct member is common to all instances (s1, s2 and s3 all share the same value of i so if you change s1.i s2 and s3 will also have the changed value.
Static data have storage and initial value (default 0 but good practice to explicitly give a value) allocated at compile time before and instances are created. You therefore need to provide a definition somewhere S::i so that this happens.
By saying ‘inline’ the compiler knows you are not going to do this and it creates space for i there and then.
Others may be able to explain more clearly but I hope that helps.