The filter cutoff and resonance ('Q') controls function exactly as you would expect.
The filter keyboard tracking control sets how much the filter frequency is affected by the note being played. With this control at 'zero', the filter frequency does not depend on the note. With this control at 'one', the filter frequency rises or falls by an octave per octave that the note varies from middle 'C' (MIDI note number 60).
Like the pulsewidth section, the filter has an LFO and an envelope, and the controls are much the same. 'Filter LFO Amount' sets the amount by which the LFO modulates the filter cutoff; 'Filter LFO Type Amount' sets the amount by which the LFO modulates the filter type.