I am fascinated by people who know many languages!  Do you speak many languages?
  multilingualism is the use of more than one language 
How many languages can a person learn?
No limit. multilingual speakers out number monolingual speakers in the world 
Really!  That is surprising to me!  I s it best to learn many languages when young?
 multilingualism is becoming a social phenomenon governed by the need of globalization 
That is logical.  There are many languages that are similar, right?
Yes. People who speak several languages are also called polyglots