Great idea! (It's something I've been wanting to do )
I'll look at some things in addition to the basic ideas that @Intellection74 has covered
Some more basics:
The range for hue repeats every 360 increments, meaning 0 and 360 are the same colour, 1 and 361 are the same and so on.
Lowering the saturation is the equivalent of adding white, and lowering the brightness is the equivalent of adding black.
This system is based on how human eyes perceive light. Most humans have three types of cones (a kind of cell) in their eyes that are responsive to red, green and blue light wavelengths. Pixels use this system to display images. Extra information in the form of a video here if you're interested in how we see light.
HSB may feel a little more intuitive to use compared to RGB because of how mixing works in RGB, depending on what you are shown in school. RGB is called an additive mixing model and in the image below on the right is how the mixing turns out in RGB, compared to what a lot of people are taught for mixing paint colours on the left.
So red+green=yellow, green+blue=cyan and red+blue=magenta in RGB, which is different to what you might expect. (Because that's how our eye sees light, if you shine red light and green light, it would appear yellow to your eyes.)
There are other variations on colour models too aside from HSB and RGB (such as CMYK, HEX) and if you come across colours in any of these other models and want to use them in Hopscotch, fortunately there are a lot of online colour converters you can search up and use.
Sources: I first learnt everything about HSB and RGB from this great explanation on colour models and this great explanation on HSB, both from the same person. (They sum these ideas up really well.)
Difference in range:
The total number of colours you can get with HSB is
360*101*101 = 3,672,360. This comes from a range of 1-360 for hue, 0-100 for saturation and 0-100 for brightness.
The total number of colours you can get with RGB is
256*256*256 = 16,777,216. This comes from a range of 0-255 for red, 0-255 for green and 0-255 for blue.
(Clearing a possible misconception — these are whole numbers since it seems the app rounds off, so I don't think the colour range isn't infinite as some people have called it. Our eyes (referring to the majority of human eyes with 3 different cones for R,G,B light) can't really distinguish small changes anyway, like a change between hue 240 and hue 241.
However, roughly 3.7 million colours with HSB and 16.8 million with RGB is very huge! You can keep it in mind but our eyes probably won't tell the difference between a lot of the colours.)
Some other things to note:
For red, green, blue, saturation and brightness values on Hopscotch (basically all values except for hue), whenever they go above each of their ranges, the app processes the number as if it is 0. For example, if you set the brightness of a colour to 101, it will look like it has a brightness of 0 instead.