Tables and functions are objects. Variables do not actually contain these values, only references to them. Tables are also used in what is known as object-oriented programming. Functions that deal with a particular type of value are part of that value. Such a value is called an object and its functions are called methods. In Corona, we'll be focusing more on display objects since they are essential for game development.
Anything drawn to the screen is made by display objects. In Corona, the assets you see displayed in the simulator are instances of display objects. You have probably seen shapes, images, and text, which are all forms of display objects. When you create these objects, you'll be able to animate them, turn them into backgrounds, interact with them using touch events, and so on.
Display objects are created by calling a function known as a factory function. There is a specific kind of factory function for each type of display object. For example, display.newCircle...