As is the case for all "localized" versions, the software itself should work fine.
Hwever, it may be in the language of the country it is sold in, for example the version of MS Office 2011 sold in Japan is localized, and the menus are all in Japanese. There are also some minor differences, line spacing for example to accomodate the two-byte Japanese (Chinese) characters. Every country has its own version. Make sure the version you buy is in a language you can read!
Some software allows for the user to set the language displayed, but I have found that rare, rather than common.
I do not know about Parallels, but I believe Windows 7 is also localized (English versions may also be on sale).