Coffee does not stain quartz countertops if wiped up quickly. Quartz countertops have many benefits, one of which is that they are non-porous, which means that they don’t absorb anything that you may have spilled on them. If you do happen to spill coffee all over your quartz countertops, just wipe it off with a towel, then clean it with a little water and dish soap, and wipe dry.
If the coffee has had a chance to dry on there, follow the same procedures. If the coffee spill is too stubborn to come off with just soap and elbow grease, then make a cleaning solution of about 90% rubbing alcohol and 10% water to attack the residue. Though, it should be noted that anything you let sit long on the countertops does have the potential to stain it — especially if it is acidic.