The best way to learn what these do is by seeing how they’re used. It may sound confusing, but I promise after this, it’ll look simple. You could achieve this by creating an automation clip linked to the volume of each instrument channel or mixer track. Let’s say you want your drums to slowly decrease in volume as an airy synth increases in volume. to vary the behavior of said button, slider, or knob, with time and without the user actively engaged.
This basically means they’re pieces of software code within FL Studio that can be linked to different buttons, sliders, knobs, etc. They are part of a larger group of features in FL Studio and many other DAWs that are formally known as internal controllers. An automation clip (or envelope) can automatically control the behavior of a parameter or group of parameters in FL Studio.