Can you please explain to me the last line? I have never used the class called pairs or used a method called map. Please help

Anytime :)

Oh Wow. That is a very handy concept. I will use that from now on.
Thank you very much for taking your time :3

It's called a ternary operation; it's a short-hand if else statement. The syntax is as follows: Boolean ? True : False. It's a pretty old operation and is used in Java, JavaScript, CoffeeScript, C++, Ruby and others.

The code above arr[5]=="loses" ? one-two : one+two; first looks at the boolean expression before the question mark and if it evaluates as true, then it look at the first statement after the question mark. If the boolean expression is false, it will look at the second statement after the question mark.

It's equivalent to

if (arr[5] == "loses")
  return one-two
else
  return one+two

For more information, you can read about it here, and here.

What is the second last line doing? I have never seen the use of those question marks and ' : ' in c#
Is that some kind of new feature?

As a beginner of foreach statements, i find this rather fascinating :3