From the speaker's point of view, as others mentioned, it's the light bulb. If you take the two side of the wire that connect to a light bulb and you touch them together, bad things will happen, because there's no resistance at all and the current flows way too much. Hopefully there's a fuse in the circuit designed to blow when that happens. When light bulb is in the circuit it resists the flow, so that it doesn't flow too fast, and it also just happens to make a nice light in the process.
The speaker acts as the same sort of resistance to the amp trying to push electrons through it. If you connected the two sides of the speaker cable together, you'd probably blow up the amp or trip a fuse in it, because there would be no resistance to the electron flow.
But, like the light bulb, it can only provide so much resistance. If the pressure being applied is too high, something in the path will fry, just like a light bulb filament will burn out if you apply too much juice to it. That's why speakers have power limits set for them.
That's also why amps have limits on how low the ohms (resistance) on the speakers can be. If it's too low, there's not enough resistance to the electron pressure and it's like a slightly less bad version of touching the wires together with nothing in between. The speaker won't be bothered, AFAIK, but the amp will not see enough resistance and start pumping electrons at a greater rate than it is designed to handle.
Anyway, probably no clearer than anyone else, but I can never resist the challenge to be less understood than my fellow man.