It was the first to present the concept of creating a function without a superfluous keyword function, replacing it with something that in 2015 was to become the function arrow (=> in ES6, -> in CoffeeScript). He also got rid of the curly braces (like Python), replacing them with indentations. Often in CoffeeScript, you can omit (once required) parentheses, that often unnecessarily decrement the readability of the code.

CoffeeScript is to Ruby as TypeScript is to Java/C#/C++.

If you love Ruby, you'll enjoy CoffeeScript as it makes the JavaScript more like the Ruby.