The VCF-01 is a 2 pole resonating low pass filter with frequency modulation.
The frequency knob changes the cutoff frequency.
The resonance knob controls the amount of feedback in the filter.
The control voltage amount knob applies the CV socket input to the frequency.
Control voltage input for cutoff frequency modulation
Low pass output.
12db per octave
0 hz to approx 7 khz
A low pass filter allows frequencies below the cutoff frequency to pass through while attenuating frequencies above the cutoff frequency.
High resonance values will emphasize the filter frequency and slightly reduce the amplitudes of all other frequencies.
You would typically filter waveforms with lots of harmonics such as sawtooth and square. Filtering a sine wave will have minimal effect.