2 (2 channels-can power two separate speakers) x 100w (watts-power) rms (root mean square-a kind of quantifying a signal) at 4 ohm (this is the impedance of the speaker)
pag 2 ohms lang ang impedance ng speaker mo, mas tataas ang power na madedeliver coz power = current x square of the impedance
about your speaker, it can produce sound when you can supply it with power ranging from 150-180watts rms (ata, not sure) and usually, the impedance of automotive speaker has 2 ohm impedance.