In addition to being able to create multiple separate MSIs for each language, it's also possible to create a single MSI that shows a different language depending on the end user's language settings. The process is automatic for the user. They don't need to choose the language.
To get started, build separate MSIs for each language. For a simple example, add a project reference to WixUIExtension. Then add a UIRef element to your markup to reference one of the standard dialog sets and set Cultures to Build in Visual Studio to es-es;en-us;de-de. This will build Spanish, English, and German installers using the .wxl files that are embedded in WixUIExtension. This is depicted in the following screenshot:
Build the project. Visual Studio, by default, sends the output of each localized MSI to its own folder.
Each folder contains an MSI for a different language. To merge these...