A polyglot is a person who is multilingual. English might be his first language but he has also learned a second language, a third and so on.
A polyglot can communicate fluently and proficiently in different languages aside from his native tongue. Not only that, he can also speak and understand many languages and can also write them well.
Another quality of an English polyglot is that he can both listen and read the languages of other nations. He may know 2 or more other tongues aside from his native tongue.