Methods Part 2

Im trying to understand the sort method here. Let me start off by explaining what I do understand so you can see what im missing. I understand line and and 2 but what is confusing to me is how javascript is making a and b represent the values in the array. The other confusing part of this is after you figure out if the value is negative or positive how does that value get put back into the array. I have an idea but Im not sure so tell me if im wrong. Does the function use a and b to represent 10 and 44 then determines it has a negative value so it places a 10 before 44? Then is the next step to take 44 and 32 and do the same thing? That would place 10 first then 32 then 44. It seems the disconnect on this question is figuring out how a and b represent the values in the array and then how those values are placed back in the array. Since both of those actions at least to me seem like they would require more code.

var my_array = [10, 44, 32, 100, 0, 44, 3, 4];
console.log(my_array.toString());

my_array.sort(function (a,b) {
  return a - b;
});
console.log(my_array.toString());