The leading edge is a metaphor. It is the item that makes you “enter into”. Useful English allows you to enter into many business, cultural, strategic situations.
Question on Quora : What are the benefits of learning a foreign language like English ? (1)
What is “English language” ?
(1) My first answer :
When I was young, university was a playground for me (I never went to any class) so I had no diploma.
From my 20’s onward I found jobs because I knew English.
In electronics, then computer science then human sciences I could be a self taught person from English books and courses.
At the age of 50 I decided to “go to school” i.e. take a card for it. I wrote a master’s dissertation alone from English documents, went to the university, gave them the dissertation and said politely : “May I have a master with this research work” ?
They said “Yes !” and accepted me for a PhD.
A fellow student asked the lab boss : “But how will he make his PhD without being in the university ? (I lived 400 km from it).
And the boss answered : “He will do his PhD in his kitchen with English publications. ”
So did I !
“Nobody is a prophet in his own country … but if he masters English !”
P.S. : I simplified my true story but not that much
Agora mundi 
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