By default, the Facebook app for Android will run in the language option set on your device. However, if you'd like to use a different language on the application, you can adjust your language settings in just a few simple steps. Here's how to do so.
Open the Facebook app and tap the Menu option. Then, scroll to Help and Settings.
Next, select App Settings > General Settings:
Tap the Language option, and then make your selection:
Your new settings will be applied right away.
Image: © Andrey Yanevich - Shutterstock.com