This app isn't available on the United States app store, and is only available in some countries, however the functionality of the app is flawless if you manage to side load it. I personally would target this at people who feel like myself, that the regular Facebook app was simply bogged down and very slow.
For countries that support it the official link :
https://play.google.com/store/apps/details?id=com.facebook.lite
For countries that don't support it (like the USA). :
http://www.apkmirror.com/wp-content/themes/APKMirror/download.php?id=4343
For countries that support it the official link :
https://play.google.com/store/apps/details?id=com.facebook.lite
For countries that don't support it (like the USA). :
http://www.apkmirror.com/wp-content/themes/APKMirror/download.php?id=4343