Extracting Data from Inside a Parentheses

[crazybeauti_ful]

Hi,

How do I extract 'Belgium' from 'BE (Belgium)'?

I looked for solutions here but somehow, I am only getting 'BE' as output.

Thank you.

[ImanJanahmadi]

Hi,
This method worked perfectly for me! However, I am not familiar with the terminology applied in this formula! Is there a doc or textbook for that to read? 

Thank you 

[YaGurlKate]

I've found this Regex cheat sheet to help tremendously!