"Advantages of knowing English" English is the international language. About 85% of all knowledge in the world is available in English, more than twice that of any other language. It is the language of international diplomacy. If you want to be an airline pilot, and fly to different countries, you must know English. If you want to be a doctor, English is the standard language, etc., etc. English is studied as a second language more than any other language of the world. In fact, there are more people in China who speak English than in the U.S.A. [Just how well they speak it is another story.] In many former colonies of Great Britain, English is the official language of the government. This is because it is considered to be neutral. 
There is nothing about English that makes it intrinsically better than any other language. It is just a circumstance of history. But that's the fact of life in the world today.