Especially in the beginning, learning and practicing vocabulary is the main part of language acquisition. There is no way around it. However, not all words are created equal. It’s important to concentrate on words that’ll give you the most bang for your buck.
In terms of language learning, the most bang means how likely it is that you are going to use a particular word in everyday conversation. That’s where word frequency lists come in.
You don’t need to learn all that much for functional fluency. The 1,000 most common words in German make up about 80% of the written language. So if you concentrate on those first, you will make a big dent in the amount of German you will be able to understand. It’s the easiest way to learn German words that you’ll actually need in real life.
Languages don’t evolve in complete isolation. They mix in the same way as the people who speak them, and are as intertwined as family trees. Everyone borrows from everyone else and German is no exception.
This is good news if you want to learn German fast because of so-called “cognates.” Cognates are words in two different languages whose spelling and meaning is so similar that they are easily recognized and understood.