This is just a very simple brainfuck interpreter written in C#. For more info on the language itself, see the wikipedia article at http://en.wikipedia.org/wiki/Brainfuck

From Wikipedia, the example Hello World program is as follows
++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>.
This prints Hello World! to the standard output