“Vocabulary” as it is used in the context of tokenizers is not the same as the common English definition of “vocabulary”, i.e., a tokenizer doesn’t necessarily break up a text into intelligible English words.  You may want to read up on how tokenizers work:

  
      
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Summary of the tokenizers 3

On this page, we will have a closer look at tokenization. As we saw in the preprocessing tutorial, tokenizing a text is splitting it into words or subwords, ...