This is the 466th most frequent Chinese word.
关于
"About" or "regarding."
The word '关于' in this sentence introduces the topic of discussion, which is 'this project'.
关于这个项目，我们还有很多事情需要讨论。
Regarding this project, we still have many things to discuss.
Here, '关于' is used to specify the subject matter related to someone's expertise, in this case, 'world history'.
关于世界历史，他是个知识渊博的人。
Concerning world history, he is a knowledgeable person.
In this instance, '关于' indicates the content or subject of the notification, which is 'the new policy'.