To change the language of the Facebook app in a web browser, follow these steps:

1. Open the Facebook website in your web browser.
2. Click on the arrow in the top right corner of the page and select “Settings” from the drop-down menu.
3. Click on the “Language” option in the left-hand menu.
4. Under the “Facebook Language” section, use the drop-down menu to select the language you want to use.
5. Click on the “Save Changes” button to apply the changes.

To change the language of the Facebook app on a mobile device, follow these steps:

1. Open the Facebook app on your mobile device.
2. Tap on the three horizontal lines in the bottom right corner of the screen to open the menu.
3. Scroll down and tap on “Settings & Privacy”.
4. Tap on “Language” in the Settings menu.
5. Use the drop-down menu to select the language you want to use.
6. Tap on “Set as Default” to apply the changes.