Babel boxes (OOC) tell readers about which languages you can read and speak. it has 7 levels from 0 to 5 aside with N (native)

commons:Babel-extension-screenshot.png

See:Wikipedia:Babel

It also categorizes users by language and level. The wiki code to display the image boxes is :

Babel user information
en-N This user has a native understanding of English. fr-3 Cet utilisateur dispose de connaissances avancées en français.
Users by language