As you can see, after the "launch web browser", the shortcut is set to "WWW" by default.
I know I can change it, but I'm just curious why it is "WWW"? And how should I press "WWW"?
There are several special keyboards that bring Multimedia Keys, specially Application Keys, which include keys that have the Logo for Word, Excel, Powerpoint, Thunderbird and even... yes... Internet Explorer. When pressed, they open the app assigned to it. In Ubuntu of course this would open the Libreoffice Apps (Calc, Writer, Impress, Firefox, Thunderbird...).
The key that has the "Browser" logo, is known as the WWW key or WEB key because it opens your computer to the World Weird Web. If you keyboard has it, it will open the browser that you have set as default. Firefox is the one that comes by default but you can change this in the System Settings. Here are some images of how the key looks:
If you do not have the WWW Key, then it will simply not work. You would need to reassign the key to another value. Same thing for Volume Control, where it has Volume Down/Up, Pause and Play assign to other keys not available on my keyboard, so I need to reassign them. Here is how it looks for me on a keyboard that has no multimedia or special keys:
With this I can use CTRL with the combination of a Numeric Key (The +, -, /, * signs) and I can control the volume and any music player.