Localization
If your site needs to support multiple languages, you have several solutions available:
1) Create multiple versions of your pages (in each language). For example:
/en/about.markdown -> /en/about/
/fr/about.markdown -> /fr/about/
2) Use JavaScript and perform translations client-side (as pointed out here).
3) Use a Jekyll plugin like jekyll-multiple-languages-plugin. Note: Custom Jekyll plugins are only supported on Team, Business, and Enterprise Siteleaf plans.