Honey as a processing method sits in between washed and natural, and generally involves some measure of skin with some pulp removal before an optional fermentation stage and drying.
Depending on the coffee and who you ask, this can bring sweetness, fruitiness or soften acidity. Costa Rica is arguably the specialist in this, having a whole host of honeys available.
The amount of mucilage left on is often the first step in deciding what level of honey process is given. These are commonly denoted by colour moving from White (almost washed) to Black (almost Natural).
The least intrusive of the honey processes. Most (in some cases up to 95%) of the mucilage is removed before beans are dried. Pulping can be done wet, and sometimes the beans will be washed to reduce mucilage.
Leaving more mucilage on, yellow honey will start to have a more noticeable effect. Acidity tends to be a bit more muted, and fruitiness if any is light.
Here we start to get more fruitiness. Beans are more likely to be pulped without water, and drying may be done under shade. The colour of the mucilage will start to change and take on a reddish hue as it dries.
This is similar to a red honey but with more pulp on the bean. In some cases, 95% of the flesh is left on, it’s just the skin that is removed. Fermentation may occur, and a longer drying time often follows. As the flesh dries under the sun, the mucilage blackens until it dries.
This involves a fermentation step in addition to the methodology above. Once pulped, coffee is sealed in a tank without fresh oxygen and a fermentation step occurs before drying on raised beds afterwards.
As in any processing methodology, many nuances and variations exist. Honeys are a great starting place to understand how these can impact final cup profile if you get the chance.