Hey there! Hello!
Computer updates, especially smaller security updates, contain security information for new bugs, malware, viruses, etc. that have been written since your last update. So many of these are written for computers at any given time, meaning that keeping your computer updated is a significant step in keeping your computer's defense systems working. Paired up with legit anti-malware, virus protection software, good computer knowledge, and common sense, your computer can remain very safe from these viruses.
Otherwise, there might be some bug or irregularity within your computer's system itself that was accidentally released an update or two ago by the creators of your computer's software, which may also pose a threat for your computer system. Updating your computer can most likely fix problems like these. But, more commonly, they just keep your computer up to date on the vicious computer threats that are now available for it since the previous update.
Hope this helped you out! Feel free to ask me any additional questions if you have any. :-)
