у вас ошибка в написании метода __init__.
from tkinter import *
window = Tk()
window.geometry("800x600")
window.title("1 задание, занятие 3")
canvas = Canvas(window, height=800, width=600)
canvas.pack()
class House():
def __init__(self, roof_color, wall_color):
self.roof_color = roof_color
self.wall_color = wall_color
self.x = 100
self.y = 200
def draw(self):
canvas.create_rectangle(self.x, self.y, self.x + 200, self.y - 100, fill=self.roof_color, outline="black")
canvas.create_polygon(self.x / 2, self.y + 130, self.x + 250, self.y - 160, self.x * 2, self.y - 50, fill=self.wall_color, outline="black")
house = House('green', 'red')
house.draw()
window.mainloop()