Can you speak Japanese?
How about Arabic or Korean?
Imagine you are testing a product localized to Arabic language (or any other language you don't know how to read, write or you don't understand it). If you are familiar with the product in your language of preference then the task of finding buttons, windows and other things in the user interface shouldn't be a big problem (but yes, it still can be a pain). But what if you get an error message in that language?
You would probably agree that it can be very hard to quickly find someone who speaks those languages. There's a Live Translator website you can use to translate the error message or any other text. There's also an addin up on Windows Live Gallery which adds a Translator button to your IE and can translate the web page you are currently looking at to 12 languages. Even though the translations are not perfect, it's usually enough to get the idea what the error is about.
If you don't like using machine translation there could actually be a second 'solution' to your problem - you can always install the product in language you understand and try to get the same error message. But what if you don't get that error message? Even if you do get the 'same' error message - can you tell with 100% certainity that the error message in let's say English language is the same one you are getting in other languages? That's the other story. Maybe there is a bug which is specific to the localized version? You should definitely verify that.