What is the meaning of x={0} and y={1}? Why is this particular? How it'll vary?

Answer 1

its that if we want display diffent parameter we use to write in index form , which variable want to display first

Answer 2

int x = 1;
int y = 3;

Console.WriteLine("x = {0} , y = {1}", x, y);

output: x = 1 , y = 3

the {0} in the string is replaced by the first variable after your string input which is x in this example you can put as mean variables in as you like {1} {2} ....{5179}