We have already seen in my last article, that you don't need to have a perfect English to be understood.
On the contrary, if your level is too high, it could be penalizing if you want to communicate with non-anglophone people.
But in the business world, you need to have a good enough English level.
Overall, you need to learn business vocabulary related to your professional activity.
As for the studients, English knowledge will ease their entry in business world.
If you want to learn a language efficiently, you have to learn the most usefull vocabulary.
It is suggested to aim professional and business English, to be more competitive and in order not to loose too much time.
For example, if you learn specific vocabulary, you will be able to have a phone conversation and write professional documents (mails, notes...);
According to the author of the book, people who are specialized in professional vocabulary are more efficient and operational.