Woo, that is a hell of a definition. So let's minimise it a little bit and break it down individually for better understanding.
It is also a multi-paradigm language, meaning that it is so flexible and versatile that we can use all kinds of different programming styles. Such as imperative and declarative programming. These different styles are unique ways of structuring our code; again, you will learn about this throughout this course.
Also, in computing, just-in-time (JIT) compilation (also dynamic translation or run-time compilations) is a way of executing computer code that involves compilation during the execution of a program (at run time) rather than before execution.
To break it further, let me give an example to make you understand from the knowledge you already have. Nowadays, you might come across apps with a mobile application and a browser-based website, which looks and functions similarly in the majority of the cases.
Again, you will learn all about these throughout this course and eventually get the hang of it.