Most likely it's with regard to powered electronic devices, which might require some national safety inspection authority to certify it. It's the same in many areas of the US where UL inspection is mandatory, CSA in Canada, DIN in Germany, etc. However, given that a guitar produces a fraction of the amount of power that the tiniest flashlight does, this should not be an issue but of course in China, one can never know anything for sure!
You might want to have the owner's manual handy (or download one from the official site) so that you can point to the CE sticker on the back page; that seems to be generally recognized worldwide, even though it's strictly European.
I'll speak from my experience: in 2005, I decided to move from Taiwan to Beijing, China to continue on my music production/engineering career after working here for a few months. After cargoing up my books, LPs, CDs, computers, Hi-Fi systems, Marshall stack, less valued guitars, and furnitures that my wife couldn't live without to be transported into China by way of sea, we got on the plane with our baggages and 2 of my Rickenbacker basses in their cases covered in bubble-wrap. The Beijing airport custom didn't even bother to stop us to inspect on our stuffs. The officers were easy on people bringing in musical instruments. Many of my friends have similar experiences. Just let the custom officers know that you're a player and not intending to sell your guitar in case they ask.
Guangzhou is a humid place all year round, so the first thing to do after arrival is buy a dehumidifier and a hygrometer (in any home supply stores which are easy to find in the city) to make sure the relative humidity stays in the 35~45% range in the space where you store your guitars.
Good luck on the move!
I have lived in China for over a decade working as a business/finance professor. I'm originally from Canada. I retired from academia last year and have fallen into my new "careers" of guitars & motorcycles! I have a "boutique" of very high end premium guitars in Beijing. It isn't really a "shop", per se, as my buddies and I usually just hang around, trying to pretend we are rock stars! And then we hop on our horribly obnoxious and loud cruiser motorcycles and go for a ride through the mountains around Beijing. Life is tough.
I've a collection of several dozen guitars with me in Beijing, including some Rics, and (as Paul mentions) there has never been any issue coming through Customs, as long as the guitars are for personal use. I have also imported several expensive guitars for resale, and it is effortless (well, as long as one pays the duties and taxes, which are actually quite reasonable).
The only story I have heard about China Customs relates to counterfeit guitars - you can get into very deep doo doo if you play around in that game. BTW, we "bikers" offer free set-ups to anyone with a fake guitar ... one end of a rope attached to the back of our bikes, the other end attached to the neck of your fake guitar.
The China of today is VERY different from when I first came in the late 90s - I can't imagine what it will be like in another 10 years.