In general terms -
Series means wiring two items together end-to-end, plus to minus. With speaker impedances (ohms ratings) the ohms total of the combination is the sum of the two. Ex. two 4-ohm speakers in series = 8 ohms.
Parallel means wiring items "across" each other, Plus to plus, minus to minus. With 2 speakers (or 2 voice coils of the same speaker), putting them in parallel creates a combination that is half of each. Ex. two 4 ohm speakers in parallel = 2 ohms.
Bridged means the same as series, but refers to amp outputs instead of speakers. You can take a 2 channel amp and connect the both channels in series and run them into one speaker for more power. That's called bridging the amp.
1999 Buick Park Ave Ultra
Head Unit: JVC KWHDR720
EQ: Audiocontrol EQL
Front Stage: Hybrid Audio Technologies Imagine 5.25 mids, Morel Maximo tweets
Sub Stage: Boston G3 10", 0.5 cu ft sealed
Amp: PPI Phantom 900.4
Rear Fill: Boston SE953 6X9's