Capacitors are little storage devices for electrical charge. They help to provide energy when needed, filter signals, decouple circuits, time in circuits, manipulate control voltage, prevent noise in signals and more. Besides that, they block DC and allow the flow of AC in a circuit.
The operational amplifier is one of the most versatile and useful components in electronics. The op-amp can be used as an amplifier, attenuator, filter, mixer, comparator, integrator, oscillator, rectifier, peak detector, clipper, and more. So op amps are great building blocks for synth DIY.
Once you start to read datasheets and schematics, you run into scientific notation and metric prefixes of values. Engineers use their own flavor of scientific notation, called engineering notation. It’s based on the metric system and easy to use.