when the car is running, under the hood, I find this piece of round cover sometime turn with the wheel under it, sometime stop, and I can hear clicking sound when it change from turn to stop or stop to turn.

Please tell what'* the problem, how can I fix it, Thank a lot

As the experts below pointed out, it'* the AC compressor and It'* normal for it to turn on and off. Thanks again.

That looks like your A/C compressor. The A/C clutch is supppose to turn on and off when either the A/C or defrost is on.

That isn't the starter. The starter has no belt.

That is your AC compressor, and it'* normal to click on and off as the compressor needs to cycle to maintain temperature in the car.

If you turn off the AC, that will stop engaging the compressor.

FYI, the topic title did say Starter before it was edited it. Just so you all don't think I"m senile.

That is normal operation. Ignore it.