1. def calculate_rectangle_area(length, width): : This line defines a function called calculate_rectangle_area . Functions are reusable blocks of code. This function takes two arguments: length and width .2. """Calculates the area of a rectangle...""" : This is a docstring, which describes what the function does. It's good practice to include docstrings in your code.3. area = length * width : This line calculates the area by multiplying the length and width.4. return area : This line returns the calculated area to the part of the program that called the function.5. length = float(input("Enter the length of the rectangle: ")) : This line prompts the user to enter the length of the rectangle and converts the input (which is initially a string) into a floating-point number (a number with a decimal point). We use float because the length might not be a whole number.6. width = float(input("Enter the width of the rectangle: ")) : This does the same for the width.7. area = calculate_rectangle_area(length, width) : This line calls the calculate_rectangle_area function, passing the user-provided length and width as arguments. The returned area is stored in the area variable.8. print("The area of the rectangle is:", area) : This line prints the calculated area to the console. This is a very basic example, but it demonstrates the fundamental concepts of a computer program: taking input, performing calculations, and producing output. More complex programs use similar building blocks but combine them in more sophisticated ways.