It's easy to get confused by the names of large numbers in German, as many of them are false friends — number names that are the same as in English but represent different numbers entirely. Let's start relatively small with a mere million:
Rund eine Million Menschen wird in der Stadt erwartet.
Around one million people are expected in the city.
Captions 23-24, Rhein-Main-TV: Feier zur deutschen Einheit in Frankfurt wird gigantisch
Thus "million" in English is the same as die Million in German: a 1 followed by 6 zeros, 1,000,000. But when we ramp it up to an English billion, we find our first false friend:
Drei Milliarden Jahre lang war kein Lebewesen auf der Erde mit bloßem Auge zu erkennen.
For three billion years no living thing on earth was visible to the naked eye.
Captions 19-20, Zeit: Die Vergangenheit und Zukunft von allem
An English billion is die Milliarde in German (plural Milliarden). That's a 1 followed by 9 zeros, 1,000,000,000. Let's get even bigger with our next false friend:
Ich bin eine aus sechs Billionen.
I am one of six trillion.
Caption 7, Frida Gold: 6 Billionen
An English trillion is die Billion (plural Billionen) in German. That's a 1 followed by 12 zeros, 1,000,000,000,000. I'm not sure what Frida Gold is referring to, since the population of planet Earth is 7.4 billion (in English, 7,4 Milliarden in German), so even if she means the English "billion," the count should be 7 billion, not 6 billion! Maybe it just sounded better in the song...
So let's recap what we've learned and go a bit further (false friends are highlighted in bold):
English / German
Million / die Million (1 plus 6 zeros)
Billion / die Milliarde (1 plus 9 zeros)
Trillion / die Billion (1 plus 12 zeros)
Quadrillion / die Billiarde (1 plus 15 zeros)
Quintillion / die Trillion (1 plus 18 zeros)
Sextillion / die Trilliarde (1 plus 21 zeros)
Septillion / die Quadrillion (1 plus 24 zeros)
Octillion / die Quadrilliarde (1 plus 27 zeros)
Nonillion / die Quintillion (or: die Quinquillion) (1 plus 30 zeros)
Note that all plurals of these high-count words in German end with -en.
Take a look here at the complete list of names of large German numbers and do a search for some big numbers on Yabla German and see some more examples of how they are used in German in a real world context!