I’m willing to bet that most Salesforce projects only use a single language. However there are times when more than language is needed.
When that case arises, the main tools used are Custom Labels and the Translation Workbench (TW).
Labels are easy enough to work with. Instead of using a hardcoded string, you create a label first, and then use the label instead of the string. Labels can be translated to any other language.
The TW is significantly more challenging to use. Mostly used to translate screen flows, translations are usually exported, updated, and then re-imported.
If something is off by a space or comma, it fails. And errors are caught synchronously. This means if there are 12 errors, it’ll only report the first. When you correct it, and try again, it’ll report the 2nd. And so on.
The takeaway
While supporting multiple languages isn’t easy, sometimes it’s necessary. You just need to have lots of patience.