(Disclaimer) This is a simplification which I hope helps.
DSP makes a big difference to the way a keyboard sounds. The more basic models don't provide any; the Genos provides lots.
Your keyboard contains DSP types that you can apply to voices and style parts. Two or three hundred to choose from, and on Genos you can have different effects on different parts at the same time.
But in fact, there are only a few basic effect types. Each of those effect types have lots of ways they can be adjusted. So when you select a DSP from the list, it's a basic effect type with a particular set of adjustments. You are free to make any more adjustments you want.
This is the key to getting to grips with the large number of DSPs you are presented with - recognise that there are only a few themes and lots of variations.
The basic types are common across all types of instruments and manufacturers. They include chorus, reverb, delay, phaser, flanger, disortion, rotary speaker. You can look these up online to get more detail about what they do. You will find that most of the material talks about different makes of guitar effect pedals, but that's OK if you just listen to how the effect modifies the sound.
Pick a voice, select a DSP and listen to what it does. The name of the effect should give a clue as to which of the basic types it is. Then start making adjustments and listen to how each adjustment alters the result. You will find that some of the things you can adjust make a big difference, and some don't. If you're really interested, the online data list manual will show you the list of what you can adjust for each type.
Once you've got a bit of a feel for what the different basic types do, and what kind of adjustments you can make, you will be in a better place to be creative.
