Guillotine is an audio slicer / gate effect.
It chops up segments of audio in sync with the BPM of the track. Up to 32 divisions can be made from one section, which can then be modulated, bitcrushed, distorted, or simply silenced.
In the Sever FX setting, the top right knob can be used in Relent mode as an expander, rather than as the default noise gate – this means that the chosen segments will be made quieter rather than totally silenced.
In the other FX settings, the top right knob will operate in Inflict mode, increasing the severity of the chosen treatment.