How to parse received contours in opencv in python?

Question

OpenCV

There is a screenshot of a simple black line on a white background, I got its contours, how can I understand their specific designation and, in general, the type of representation? In the documentation, I found only a general description of the findcontours method. Where can I find a detailed description and presentation of the output data, are these contours just the coordinates of points along which lines are built, or are there representations of some shapes like rectangles?