I've seen that in more than one text.
Google hasn't helped.
The LLC Act are the laws that govern an LLC in a particular state. Each state has their own LLC Act. The laws of the state you register your LLC in are the laws that will govern your LLC. In most cases, you can override these default state laws by establishing an Operating Agreement for your LLC.
If you Google "LLC Act [your state]", you should find your state's LLC Act.