If it's a software update. Go into settings and scroll down to software update. Then just download any available update.
These updates are important and quite often come with critical security patches. But a lot of the times they are general and contain optimisations etc.
You also have another, again in settings, scroll down and tap on About Phone
Tap on Software Information and tap on Google Play System Update.
Other than that you have the usual app updates that app developers do that Google push out if you have those notifications turned on
