You can find the Documentation here:
https://github.com/emanondev/ItemEdit/wiki

Languages:
Plugin automatically select the client language [only for servers above 1.12]
unluckly not many languages has been configured by default, you can contribute sending a corrected language file to the author or edit the file on github here: https://github.com/emanondev/ItemEdit/tree/master/src/main/resources/languages