It depends. If you're trying to add support for having the content for your storefront web pages change languages based on locale, then that is an exercise for your presentation layer and is outside the scope of Broadleaf. If you're referring to changing the language that product and category descriptions are delivered in, then that is something that's currently on our roadmap. However, you could implement this yourself with relative ease by extending Product, Category, etc... and adding two new Map structure fields for name and description keyed off of locale whose values were the different language content. Then, you would override the implementation of getName() and getDescription() to determine the current locale and then retrieve the proper value from your new maps.