Unicode is the standard that most computers use to define what text characters exist and how to encode them. In the bad days before Unicode (e.g. the 1990s), different computers used different characters and stored them different ways. If I used Russian and you used Japanese, we couldn't exchange files. But with Unicode, everyone's computer handles characters the same way. I can send you Ӂ ڠ ᅗ Æ א ₳ ☢ 五 and your computer can handle it (as long as you have the fonts installed).

The point is that computer companies aren't going to patch random characters into their OS. But if you get a character added to Unicode, then everyone will support it. The Unicode Committee has the people who decide what goes into Unicode. The purpose of my proposal is to convince them that putting the Bitcoin symbol into Unicode makes sense and isn't just some crazy idea I came up with.

(I've oversimplified somewhat but this is probably already more than you want to know about Unicode.)

Ken