The IF101 is an analog multipler that can be switched between two-quadrant and four-quadrant operation and so can function as a voltage-controlled amplifier (VCA) or as a ring modulator (RM).
Operation is the same as for any other VCA and RM modules.
As a standard VCA, audio goes in to the [X IN] input and control voltage goes in to the [Y IN] input. The [BIAS] control can give the VCA an "initial gain", useful for AM applications such as tremolo etc.
As a RM, the "carrier" goes in to the [Y IN] input, and may be mixed into the output with the [BIAS] control. At full bias, the output is just the carrier signal with no modulation.