If you poke a pencil point into the invisible region of the film it will break. The top half of this soap film is much thinner than a wavelength of light, under 300 nm thick. The soap film is a water sandwich. A layer of water is held between two layers of soap molecules. When the soap film is vertical the water drains down under the pull of gravity so that the top of the film becomes thin while the bottom becomes thick.
Light reflects from the front and from the back of the soap film.
The two reflections add up producing interference of light. Different thicknesses of soap film cancel different colors. This produces the bands of color you see in the film can. The light waves reflected from the front of the soap film are inverted while those from the back are not. Thus, soap films that are thin compared to all wavelength of light reflect no light at all.