Python Step_by_Step_Explaination

Someone shared a code with me but I cannot get it to work. If you are able to review the code to spot any errors and provide me with step-by-step instructions, that would be helpful. I am attaching the code and the file I want to use to detect the shapes. Remember, I am new to python, so I do not know much about it. Your steps should be clear, as I am using PyCharm to type the code. It should provide clear step by step instructions that can be easily followed by someone that is new to coding, just needs instruction.