Serbia is not a member of the EU or part of the Schengen Zone. This can be a blessing since you will not need a Serbian tourist visa as Chinese citizen. So you can visit Serbia visa-free, however, this will not give you permission to visit any other Balkan or European country. But, if you have a valid visa to visit the Schengen Zone (or a few other places), Serbia will give you visa-free entry and it will not count against your time in the Schengen Zone.