CMYK Color Mode is what we use in the printing.
First, we need make sure that the artwork we open in the Adobe Illustrator is working under the CMYK mode. Click File — Document Color Mode — CMYK Color Mode
Second, click Window — Seperations Preview to open the Seperation Preview window.Then check the Overprint Preview checkbox. Here we will know the color number to be printed.
Third, click on the eyeball icon in front of each channel name in the Separations Preview panel to turn off visibility for all separations, then turn on visibility one CMYK channel or spot color at a time. If the artwork has no change when you click on a chanel, it means that color exists. Not otherwise.