So, Nahj al Balagha is like a really cool book that has a bunch of important words that a man named Ali ibn Abi Talib said a long time ago. He was really smart and people liked listening to him because he could explain things in a way that was easy to understand.
In Nahj al Balagha, you can read what he said about all sorts of things like how to be a good leader, how to be a good Muslim, and how to be a good person. He also had some really interesting stories to tell.
It's kind of like a big magnum-opus of all the things he said that were important, so people can read it and learn from him a long time even after he died.
People still read Nahj al Balagha today because they think it's still important and helpful to learn from his advice. It's like a big treasure chest of knowledge!