What is "object representation" in OOP design patterns terminology?

I am learning about OOP Builder pattern and definition from the GoF books says:

The intent of the Builder design pattern is to separate the construction of a complex object from its representation. By doing so the same construction process can create different representations.

I am trying to understand this but I am not sure what is meant by the "objects representation". So what exactly is an "object representation"?

Can one specific object have multiple representations or just one? Is "object representation" a synonym for "one specific instance of an object that is instantiated from a class"?

I am C# programmer so explanation or example in this language would suit me.