In simple terms, localization can be defined as the process of translating websites, software, documentation, etc., into the language of a specific target audience. It is also concerned with ensuring that a product's content, style, graphics, and cultural conventions – such as currencies, dates, units of measurement, etc., – are appropriate to the country and language in which it is to be used.
Localization is a very unique form of translation; It can be thought of as more of adapting than just translating the source text.