I have a 3 hour stopover in Guangzhou. Are there restaurants/cafes in the airport building?

Yes, there are lots of fast food restaurants, Chinese food and western food restaurants in terminal buildings, such as MacDonald and Chinese Dumpling.
In addition, cafes such as Starbucks and U.N.D.C Coffee are also located in the airport.
Enjoy your rest time!

Thank you Evelynn from Poland. That's a big help and a relief.
Could you tell me where in the terminal buildings -- are they in international or domestic terminals?
I will be changing to a connecting flight to X'ian.