A class and a function to create and light up buttons in PyGame
I think your button class should do more. It should know if a point is within it's boundaries or not and what its image(s) is (are). It should probably also have an update method that can optionally be called with the mouse position. I would also rename it to singular Button, since each instance of the class is a single button and not a collection of buttons.

class Button:
    """
    This class takes the x-position and the y-position, width and height of an image.
    """
    def __init__(self, x, y, width, height, image, hover_image=None):
        self.x = x
        self.y = y
        self.width = width
        self.height = height
        self.image = on_image
        self.hover_image = hover_image

def point_inside(self, pos=None):
    if pos is None:
        return False
    return (self.x &lt;= pos[0] &lt;=  self.x + self.width \
            and self.y &lt;= pos[1] &lt;= self.y + self.height)

def update(self, screen, mouse_pos=None):
    if self.hover_image is not None and self.point_inside(mouse_pos):
        screen.blit(self.hover_image, (self.x, self.y, SCREEN_HEIGHT, SCREEN_WIDTH))
    else:
        screen.blit(self.image, (self.x, self.y, SCREEN_HEIGHT, SCREEN_WIDTH))


if __name__ == "__main__":
    thumbs_up_img = pygame.image.load('thumbsup.png')
    thumbs_up_lit_up_img = pygame.image.load('thumbsupred.png')
    thumbs_up = Button(60, 240, 50, 50, thumbs_up_img, thumbs_up_lit_up_img)

    # some pygame setup
    ...

    while True:
        mouse = pygame.mouse.get_pos()
        button.update(screen, mouse)
        pygame.display.flip()


This is a bit more generic, in that it allows a button not to have a hover image and it has an update method, which is quite common for objects in pygame. You could think about off-loading the point in button boundary check to a Rectangle class, which might help since you will probably encounter rectangles and checking if a point is inside quite often in pygame.

And would you look at that, there is already pygame.Rect, from which you could inherit. It even has the pygame.Rect.collidepoint method to check if a point is inside it.

class Button(pygame.Rect):
    """
    This class takes the x-position and the y-position, width and height of an image.
    """
    def __init__(self, x, y, width, height, image, hover_image=None):
        super().__init__(x, y, width, height)
        self.image = on_image
        self.hover_image = hover_image

def update(self, screen, mouse_pos=None):
    if self.hover_image is not None \
       and mouse_pos is not None \
       and self.collidepoint(mouse_pos):
        screen.blit(self.hover_image, (self.x, self.y, SCREEN_HEIGHT, SCREEN_WIDTH))
    else:
        screen.blit(self.image, (self.x, self.y, SCREEN_HEIGHT, SCREEN_WIDTH))