Civil cases can not lead to prison time
Prison time is only available in criminal cases.
Civil cases lead to civil remedies, which are usually money or an order not to do something, very rarely an order to do something specific, but never prison time. A monetary award can be meant to make the claiming party whole (damages), to punish the sued party (punitive award), or both.
The case in question was civil in nature and resulted in a hefty monetary award for the plaintiff. The award contained both damages and punitive amounts.
Why not a criminal trial?
The problem is the statute of limitations of the actual criminal act had run out years ago, so no criminal case could be filed.
However, the statute of limitation for the civil act of defamation only started when Mr. Trump spoke about the plaintiff in a defaming manner sometime in 2019. The first case was brought timely in November 2019, while Trump was president. Since the civil lawsuit for defamation was brought timely, the case went forward. It is of note that due to the COVID-19 pandemic, during which the statute of limitations for many things was halted and thus extended, and as a result, the case could have been brought even later. In this case Mr. Trump claimed was covered under presidential immunity.
However, Mr. Trump did stop being president in 2020 and repeated the defaming statements in a statement of 2022, creating a new instance of defamation, which then was brought in a new case. As a private citizen... the case this time stuck with no defense.
There also was a Battery claim in there, which used a very narrow window opened by the Adult Survivor Act in which New York did re-wind the statute of Limitations - or rather a lookback window. This means that within one year from November 24th 2022, victims of sexual abuse after they had turned 18 can file a case to seek civil remedies regardless of the year in which the abuse took place.