Sorry if this has been answered already, but I'm trying to change the language on the page that loads when someone clicks "Forgot password" and enters their email address. Does anyone know where you can update that language?

ACP > Customization > Localization > Languages

Find the language you want to translate, and click the "Translate" button.  

You can search the phrases you want and replace them.  For example, the "Forgot Password" blurb is "lost_password".  

Thank you @Randy Calvert!!