EFF has this to say: The main mechanism of the bill is to interfere with the Internet's domain name system (DNS), which translates names like "www.eff.org" or "www.nytimes.com" into the IP addresses that computers use to communicate. The bill creates a blacklist of censored domains; the Attorney General can ask a court to place any website on the blacklist if infringement is "central" to the purpose of the site.
They go on to list sites which might be affected, including HN's own little darling, Dropbox.
I wonder often why California insists on keeping her. She almost always votes right on the environment and reproductive rights, I guess. You folks could do a lot better, though.