Google Sheets Function: RIGHT
The RIGHT function returns a specified number of characters from the right of a string.
Usage:
=RIGHT(string)
or
=RIGHT(string, number_of_characters)
Usage Example
Here, the RIGHT function will be used to retrieve the country code by extracting the last 2 characters of the reference:

To extract the country code from the right, enter the reference and the number of characters into the function:
=RIGHT(A2,2)

If the number of characters to retrieve is 1, it's not necessary to specify it:
=RIGHT(string)