im 100% canadian, I dont live in the US and wondering about your system.
so as i understand your political system, a president can only hold office 2 terms. in Trumps case, he served once already, does that mean he can only serve one more, or is the clock reset and he gets a shot at 8 years?
It's 2 total terms. There's no "resetting the clock" in that rule. Any attempt to remain in power for a third term would be blatantly unconstitutional.
That said, there's a real concern that he's likely to try anyway, and a non-zero chance that he'd succeed if he manages to fill enough of the government and military with people more loyal to him than to the constitution.
It's worth mentioning that this has only been the case since the 1950's. FDR was elected four times and died during his final term, after which term limits were added to the constitution in response.