[derriz]

It's a MIDI[1] synthesiser. You need to attach it to an external keyboard or sequencer to get any sound out of it. Think of it as analogous to network attached computer - on its own and disconnected, it's not going to do anything.

You'd typically attach it to a computer running some sort of DAW (digital audio workstation) software. Or a hardware keyboard or sequencencer.

It's "virtual analog" - which means it's trying to give the feel or controls associated with analog synthesisers which produce sound using oscillators and filters (extremely simplified description) rather than samples for example.

[1] https://en.wikipedia.org/wiki/MIDI