How is a keyboard able to play notes of so many instruments?

What I find fascinating is that a keyboard “with extensive polyphonic capabilities and sufficient instrument voices can mimic an entire orchestra”. In other words, a keyboard with these features can sound like many different instruments all at once. How is this possible? The keyboard is equipped with different MIDI channels, each channel independently assigned to a different instrument.

MIDI is an abbreviation for Musical Instrument Digital Interface. Polyphony means the “number of actual notes a keyboard can simultaneously generate”. I’m not sure how it all works but it is based on what I suspect is fairly sophisticated and complex electronics.