JIT is also known as Just-in-Time compilation. This is composed of interpreted and also compiled languages. One of the differences between JIT and interpretation is how they are used during runtime. JIT will translate the source into machine language also known as native code.
Interpreters will usually use the code that will be given by the source without having to transform it into native code. These concepts might not seem to be very hard in the beginning but the more that you understand, the better that it will be for you. There are different machine instructions that can be used for a wide variety of machines.