Luggage limits for economy passengers - carry-on and check-through

Hi, I am flying from Australia to Germany via Guangzhou with China Southern.
I found varying information regarding the free carry-on limits and free check-in baggage allowance.

As economy passenger am I allowed to:
Carry-on: 1 piece of hand luggage, plus 1 accessory [e.g. lap top]? What is the maximum weight allowed?
Check-in/through: 1 piece of luggage - free weight >>> 23kgs OR is it 30kgs?

Website wasn't very clear on that.
Please clarify the issue.
Kind regards & thank you for your help
Terra