In object-oriented programming, an instance is simply a copy of the object. In this case, there is one copy of our LearningScript file. We are using two terms here: GameObject and Object. Do not mix these up, they are, in fact, two different things. GameObject is an object in your Unity scene. It contains components such as Transform or our newly created LearningScript.
Object in programming means an instance of the script. Don't worry about the terminology too much at this stage. I am sure that the difference between these two will become much clearer soon.