Probably they forgot to remove that line or show what does it do, It's an array of character, A string is full of characters, each letter of a string is a character, you can access any of these arrays by using a zero based numbers, for example:
string a = "Hello";
// Prints e
Console.WriteLine(a[2]);
You can change this line to myChar to understand, It's same to an array of string, Which means a string is an array of chars, here's the example:
foreach (char whatever in myChar)
{
Console.WriteLine("{0}", whatever);
}