The locale definitions weblet – std_locale – is not visualized.
The purpose of the std_locale weblet is to define a set of variables with default values that may differ for different locales (regional settings). These default values can in turn be referenced in appropriate weblet properties or used in other weblet's XSL source. For variables defined in std_locale to be referenced by other weblets, the referencing weblet must import std_variables.xsl which itself imports std_locale.xsl.
This weblet is shipped in different languages with variables set to locale specific values.
For example, the std_style_v2 weblet refers to the variable $lweb_std_css_language_overlay to obtain the name of a language specific style sheet to be applied to the layout.
You can create your customized version of localizable variables, for example, if you want to customize variable $lweb_std_css_language_overlay.