What are !bang commands

It's an action that does what the author wants it too.
If your using austerity than hit ctrl+shift+X to open LSXcommand and then type !about, in the drop down select bangs to see a list of available bang commands.
You can also just right click and go to litestep and then about. However if you open LSXcommand you can test bangs in it by entering the commands, !about
You should read up on the docs and some web sites.
Mojomonkey has put together a tutorial for newbs...
I dont know the link tho...Good luck