To add additional languages for your keyboard

From the Home screen, tap the Apps Key (in the Quick Keys bar) > Settings > Language and input. Tap the Settings icon to the right of LG Keyboard, tap Input language and type, then checkmark the languages you want the keyboard to be able to use.

OR

Open the Notifications panel (when an app that allows text input is open), tap Choose input method > Setup input methods > the Settings icon to the right of LG Keyboard > Input language and type, then checkmark the language you want to be able to use.