Novum Testamentum Graece is a fancy name for the New Testament in the Greek language. You know how people talk in different languages and some of them sound funny and hard to understand? Well, the Bible was written a very long time ago in a language called Greek.
The New Testament part of the Bible was written by people who knew Greek very well, so they wrote it in Greek, not in English or any other language.
Novum Testamentum Graece is the original text of the New Testament. This means that it is the first version of the New Testament that was written in Greek.
It is important to have the original version of the Bible because many people translate the Bible into different languages, and sometimes when they translate the Bible, some of the meanings get lost or change a little bit.
So, if a person wants to study the Bible very closely and know exactly what it says, they need to look at the original Greek text, which is Novum Testamentum Graece.