Code used for decryption (java)

I am currently working on decrypting a many time pad, while looking for a way to convert XORed integer values to string I have found this fragment of code...

if ((x >= 'A' && x <= 'Z') || (x >= 'a' && x <= 'z')){}

where x is an int. However I am not entirely sure how it works, would any one be able to provide me with an explanation? If anyone needs more details please comment below rather than down voting my question.

Thank you in advance for all your answers