Facebook introduced Messenger Lite last month which works same as the main Messenger app, but the Lite version will eat less data and RAM. Though all the rich features can’t be integrated into the Lite version but it still serves the basic need. Facebook Lite will be beneficial for the countries where good internet connection is not available yet. Facebook has launched a new update recently for this app which fixes the major bugs and the overall stability has been improved. The app is new so Facebook will keep updating it with new good features.
If you want to download Messenger Lite then open Google Play and update it or go for APKMirror to download the Apk.