A brand name and model number might be helpful, or even a good picture(s) of the device showing any markings in English (markings in Chinese won't do most of us any good).
Some popular power supply devices here in North America can give either _nominal_ 12VDC (actually closer to 13.8VDC in operation), OR _nominal_24VDC (actually more like 26.8VDC in operation), depending on whether a jumper is open or closed. Power supplies usually come with an instruction sheet, and the make and model number is that key to finding that.