A parameter refers to a variable that can be adjusted to control the behavior or sound of a module. Parameters can include things like frequency, amplitude, filter cutoff, resonance, envelope shape, and more.
Each module in a modular synthesizer typically has its own set of parameters that can be adjusted to modify the sound it produces. These parameters can be adjusted using various methods, such as manual knobs, CV signals from other modules, or MIDI control messages.
By adjusting the parameters of different modules and routing signals between them, users can create complex and dynamic sounds that are unique to their particular synthesis setup.