Learning to program.

Pretty much everything ramoth said is truth.

C#, Java, C/C++, et al. are all horrid languages to begin programming with, especially for someone who doesn't want to take courses. I'm not saying they're not useful to know at some point in time, or that they are horrid languages in general (what I think of them is a completely separate topic), but if you are a beginning programmer, which of these makes more sense to you:

C#

public class HelloWorld {
    public static void Main() {
        System.Console.WriteLine("Hello world");
    }
}

PHP

<?php

echo "Hello world";

?>

Python

print "Hello world"

The signal-to-noise ratio of the C# example is horrible. There you've got OO, access control, and namespaces all chucked in there just to print something on the screen. Who cares? I just want to make text on the screen.

I don't know that I'd recommend PHP as a beginner's language, but it is pretty easy and has the benefit of being immediately useful because web pages are awesome. Does you friend already know HTML? Knowing it already would be a big help.

I've never used Ruby on Rails (which is not a language; Ruby is the language, and RoR is just a web application framework for it), but I've seen a demo and it looked pretty easy. It does a lot of magic for you so that you can make web apps a lot faster than coding everything from scratch.

In my opinion, the best languages to learn with are ones interpreted ones with an interactive mode, like Python (which I'm quite surprised ramoth didn't mention). Having a console and a prompt gives you immediate feedback on what you're doing, both with code correctness and the results of what code does. Python is a great language to play around and experiment with because of this and also because as a language it's easy to read. There are some tutorials supposedly for non-programmers here. Non-Programmer's Tutorial for Python and Instant Hacking look decent, but I just scanned them.

Jam it back in, in the dark.