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.
In simplified terms, the left hand image is true of a pure white or chrome banana and is not correct. Right-hand image is correct, of all wavelengths reflected, 580nm reflects the most and comparatively speaking the other wavelengths are partially absorbed.
The simplification of the diagrams requires you see them in conceptual terms. Technically, neither are accurate.