Hi Wlodzislaw
The Sylpyo is a monophonic midi instrument. It can generate one note at the time. Not more.
The midi signal is send to a tone generator, like a synthesizer to generate a tone.
There are several ways to generate more tones from the single note.
1/ plug the midi out in a Synthesizer with more than one oscillator. De tune the oscillators to create more notes at the same time. Note the relation between the tones is fixed.
and / or
2/ connect the midi out from the Sylphyo to synth one, and connect the midi out of synth one to midi in of synth 2 re-tune each synth to create cords.
This can be done with hardware synths and in software
Technically these are relative simple, but primitive methods, but are available NOW.
There are utilities which can create more notes from the single note from Sylphyo.
And soft synths can expand those notes as well.
And sylphyo has a way to play cords in audio. But that does not make it a polyphonic synth.
Kind regards
Frank