You should really consider ditching the Science study and going back to English because I have very little idea what you're talking about.
Parallel and Series are two different ways of wiring a circuit. In series, if part of the circuit is broken (most often by a bulb blowing) the entire circuit is broken and no light globes will glow.
In parallel, each attachment (light globe for example) is on its own circuit meaning that if the circuit is broken in one part, by one globe going out, the circuit is still complete and the remaining globes will continue to glow
