A locale defines both the language and location. For example, english is a language used in the U.S. The U.S. uses specific formatting for dates and other information that is different from other countries. As a result, the information and text displayed for english in USA would follow the display rules indicated by the EN-US locale.
Locales are used to drive translations in Freedom. This will update the page to use the translations setup for the language that is setup for the user's country. In addition to Locales, there are also Locale Collections that allow grouping of similar translations together while still allowing the display rules to remain separate when rendering for the user. This allows for translations for specific Locales, or for LocaleCollections, as needed across the system for the same language.
Language licensing is available for both a single locale and multiple locales.
The one-time fee for a given language includes multiple locales. So, you could add French and us it in Canada (fr-ca) and France (fr-fr) with ONE language license. These locales allow you to keep region specific translations separate.
Using multiple languages requires a Service Addendum and adds a monthly support fee for Translations Support. This translations support fee is not per language as it does not increase as additional languages are added.