Gets the locale of a site visitor's browser.
A locale, also known as an IETF language tag, is an abbreviated code that defines the language, country, and other aspects of a site visitor's browser, such as number format and date format.
Some common locales include:
"en-US": English, United States"en-GB": English, British"es-ES": Spanish, Spain"de-DE": German, Germany"ja-JP": Japanese, Japan"fr-CH": French, Switzerland"it-IT": Italian, Italy