If you want to install Office 2013 for two different countries/regions (say United States and Spain), you need to buy two copies of Office, and use two different Microsoft accounts to sign in. If you’ve done this and you’re still having trouble, please contact Microsoft Support.
For Office 2016, you can install a Language Accessory Pack (LAP) for Office 2016 and then switch the settings as you need to. But you can't run two instances of Word in two different languages, say in both English and Spanish. Instead after you install the LAP, you can configure your active Office language using the Office 2016 Language Preferences.
Tip: Office 365 Home allows you to install Office on two different computers, with two different languages, using the same Microsoft account.