>>21071
Around the area where you strum there's these little electric gizmos called "pick-ups", like the shipping company call line, and the vibrations from the strings that go up any of the three necks are "picked-up", like your sister, and sent through a wire to an amplifier which makes those vibrations much louder. An important note is that each of these strings have a different thickness and differing levels of "tightness", unlike your aforementioned sister, and these two factors in conjunction with one another allow one to tune the vibrations to specific audible notes. Furthermore one can press their fingers against these strings or "finger" them, if you will, which provides an even larger, like your sister, array of audible notes.
pic related, it's me.