beginner in electronics here. So you have one DC multimeter and attach one pin to lets say the plus pole of a battery and the other pin to ground/mass (<- is there a difference between those btw.? haven't found anything googeling). In my understanding there is a positive potential on the positive battery pole. And a zero potential at ground/mass (still not sure about the difference, is there really a zero potential?). Shouldn't the multimeter show the difference in potential between those two points of contact?

Many greetings from Europe