Not sure where you are getting your info, but that source is not good. Capacitance is something that arises in a circuit due to physical structures where conductors are close to one another - in those places (some intentional, some not), the circuit can store charge. Sometimes that's a useful thing, sometimes it's something you don't want. Another way of looking at it is it's a place in the circuit where energy is stored in the form of an electrostatic field.
If a capacitor is in the path of the circuit, it will block DC signals, and allow AC signals - exactly how much and at what frequencies depends on the amount of capacitance. If it's in a shunt path (a cable's capacitance does this), it will pass DC signals, and attenuate AC signals - again, the frequency and magnitude of that attenuation depends on the capacitance.
If Leo had designed his first bass guitars like pro audio gear is designed, basses would have lower output impedance, and they'd be relatively immune to cable loading - a dynamic mic, which at it's heart is a coil (just like a bass) can be run through hundreds of feet of cable without adverse effects. However, we still operate with the paradigm of Leo's earliest creations, so cable capacity is part of the sound - too much, the bass is dull, too little, the bass is shrill.