This software is based on a virtual space. An object has a position in space and a direction to which it is oriented. The orientation is defined by the direction to which the object's local axes are pointing. This virtual space is called Rhyscitlema!
Just like in the real world, there is need for some sort of camera to view an object in space. So here there is what you may call a virtual camera. It also has a position in space and a direction to which it is oriented.
In the Graph Plotter 3D software, the object being viewed is the graph of an equation expressed in terms of x, y and z. So the object is a 3D graph. Added to the equation of the graph there can be inequalities that it must satisfy. Note that even 0=0 is a valid equation!
Most importantly, absolutely everything about a graph and a camera is found (is resolved) in a single block of text. This block contains the 'features' that define the graph or the camera. These features are essentially variables and functions to which mathematical expressions are given. Absolutely any valid mathematical expression can be given. This includes expressions with vectors, matrices, functions of arbitrary number of parameters, arrays of functions, and many more.
The software uses a special variable denoted 't' which refers to 'time'. This variable 't' is used as part of a mathematical expression in order to vary with time. It essentially can be used anywhere.
In summary, the Rhyscitlema Graph Plotter 3D software is a 3D virtual environment that allows for plotting 3D graphs of equations in x, y and z, while also allowing for anything to be made to vary with time.