Locking - This term is related to check in and check out content. This is same as get lock in SVN. When you want to work on a file and require that no other user should change the content of file for that duration, then you can check out the file. Alfresco will lock the file showing a symbol indicating that someone has checked out a file to work on. When you have checked out a file, other users can still view/download the file but can not modify it. You can release the lock by check in the content (Same as SVN).
Content Renditions - In the content management world, the term ‘renditions’ typically means a facility to generate and retrieve alternative representations of content or a document. For ex., PDF format of a word file is a rendition of that file. Thumbnail created for your word/image file is also a rendition.
Multilingual - You can create multiple versions of a file according to their different language translation. Also It is possible to declare text properties that support multilingual values.
Audit- Audit helps you to keep the record of various actions performed on your content as well as for entire repository also.This link might be useful: https://wiki.alfresco.com/wiki/Content_Auditing
