Locatlization means translation of the user interface into foreign languages. This example was not Eudora, I just give it as an example of problems with localization. When someone in, for example, this mailing list tells me to use the foo command in the bar menu, I cannot find it if my menus have been translated to Swedish.
Localized software is usually more expensive to buy, in order to pay for the cost of localization.
I will buy Eudora Pro 4.0 in the U.S. the next time I visit your country. I will then disable the encryption part of it, so that the U.S. customs will allow me to bring it home to Sweden without violating U.S. laws.