You are on macOS Sierra 10.12.6 therefore there are no updates available, Apple has stopped their support for that system.
If you are looking to move to a newer OS that is called an upgrade.
The model and year of your Mac will determine which macOS you can upgrade to,
read the following links.
How to upgrade to macOS Mojave - Apple Support
How to upgrade to macOS High Sierra - Apple Support
Before upgrading make a full back up of your Mac.
Check that third party apps you use have updates available for the new OS.
https://roaringapps.com
Check that your printers/ scanners etc have updated drivers and software available for the new OS.
macOS Catalina 10.15 was released recently, the latest version of macOS.
If you are considering upgrading to Catalina be warned that it does not support 32bit apps.
Your Mac is probably running 32bit apps and these will need to be updated to 64bit apps,
some updates may be free, some may be paid. Use this app to discover which apps you have
are 32bit, https://www.stclairsoft.com/Go64/. Once the list has been created you can then
contact the developers of the apps to see if they provide 64bit updates.
How to upgrade to macOS Catalina – Apple Support
Not a good idea to have your mac set up for automatic updates. Many people have been in the middle of important
projects or tasks and an update kicks in, something goes wrong, you lose your important data, or the mac gets stuck.
You can have your mac to automatically check for updates, but before installing updates or upgrades
make a full back up of your mac.
This wisdom was brought to you from the centre of Edinburgh.