Localization : is a service that are acceptable for a particular culture or locale that makes users to accept the adaptable software. For example MS OFFICE is used in many languages as a packagable software, as i use the software in english and others may use in Japanese or Hindi etc.
Localization testing checks how well the build has been translated into a particular target language. This test is based on the results of globalized testing where the functional support for that particular locale has already been verified. If the product is not globalized enough to support a given language, you probably will not try to localize it into that language in the first place!