Python TypeError: 'method' object is not iterable

You have a number of issues in your code. For the current error, you should call the method to get its return value. Instead of background.extend, write background.extend().

I'm not sure why you want to reverse the returned tiles of tiles, but there is a simpler way than looping through sorted(enumerate(...), reverse=True). Simply do reversed(...).

The Background class's offset instance variable should be a normal variable inside the extend method as otherwise the tiles would be drawn further and further off screen. Also, use a list [0, 0] instead of a tuple (0, 0) as tuples are immutable (meaning you can't do offset[0] += self.size).

You probably also meant to use the Box class instead of the Tile class (which I'm guessing was its previous name).

I'd also rename parse -> num_tiles and extend -> make_tiles or just something that's more descriptive of what it does.

Also note that you don't need a () to define a class.

I'm not sure if the comments inside the Background constructor were part of the code, but if they were, note that comments go until the end of the line, not just the next word. Do note that keyword arguments exist in Python, so you could use those too.

Oh and if you were trying to make a chess board, you shouldn't add to both the x offset and y offset on each tile. I'll leave that as an exercise for you.

End result:

class Box:
    def __init__(self, color, rect):
        self.color = color
        self.rect = rect

    def draw(self, surface):
        pygame.draw.rect(surface, self.color, self.rect)

class Background:
    def __init__(self, rows, columns, size, colors):
        self.rows = rows
        self.columns = columns
        self.size = size
        self.colors = colors

    def num_tiles(self):
        return self.rows * self.columns

    def make_tiles(self):
        num_tiles = self.num_tiles()
        offset = [0, 0]
        tiles = []
        for i in range(num_tiles):
            if i % 2 == 0:
                tiles.append(Box(
                    self.colors[0], 
                    pygame.Rect(*offset, self.size, self.size),
                ))
            else:
                tiles.append(Box(
                    self.colors[1], 
                    pygame.Rect(*offset, self.size, self.size),
                ))
            offset[0] += self.size
            offset[1] += self.size
        return tiles

while True:
    screen.fill((255, 255, 255))

    background = Background(
        rows=5, columns=10, size=30,
        colors=((255, 255, 255), (0, 0, 0)),
    )
    for tile in reversed(background.make_tiles()):
        tile.draw(screen)