Question: I do know that there are at least two types of yellow light: a light of a single wavelength of ~580 nm and a combination of green light and red light. (Technically, there could be more yellow light.) And the following two figures are making me confused.

[![Yellow, red and green reflected (from https://slideplayer.com/slide/12783633/)](https://i.stack.imgur.com/NThcwm.png)](https://i.stack.imgur.com/NThcwm.png)
[![Only yellow reflected (from https://slideplayer.com/slide/4611001/)](https://i.stack.imgur.com/w56LDm.png)](https://i.stack.imgur.com/w56LDm.png)

Are red and green light reflected from banana? What wavelengths of white light does a banana reflect?

Answer: 
The reflectance of solid and liquid substances usually
has a broad spectrum, and bananas are no exception here.
Only gases have a line spectrum.

Here is the reflectance spectrum of ripe (i.e. yellow)
and unripe (i.e. green) bananas.

[![banana spectrum](https://i.stack.imgur.com/B4vH5.jpg)](https://i.stack.imgur.com/B4vH5.jpg)  

(image from "[Food chemistry - Prediction of banana color and firmness
using a novel wavelengths selection method of hyperspectral imaging](https://doi.org/10.1016/j.foodchem.2017.10.079)")

You see, ripe bananas reflect light beginning from green (~ 520 nm)
through yellow, orange, red, and extending to infrared.
Narrow-band yellow is indeed [metameric](https://en.wikipedia.org/wiki/Metamerism_(color)) to some wavelength combinations like green/red, green/yellow/orange/red etc.. But if you see a yellow-reflecting surface, you can be sure\* that its reflectance spectrum is not just a narrow-band yellow. It must be a broadband green/yellow/orange/red reflector. If you find an actual surface that has a narrow peak of reflectance at the yellow wavelength and nothing else, this surface will look dark brown, because it reflects only the tiny portion of light incident on it, compared to a broadband reflector.

So, the short answer is that the figure on the right is grossly misleading, and a banana reflects much more wavelengths than just the yellows.

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\*Unless it's fluorescing with a narrow-band yellow, which would be unusual