There is no update to your OS but there are many upgrades.
Software update, upgrade--what's the difference? - http://support.apple.com/kb/HT1444 [No longer directs to a document discussing this but basically an upgrade is a major system release such as replacing OS 10.10 with 10.11, and an update is a minor release for a particular system, such as taking 10.4.8 to 10.4.11. Software Update will check for updates but not necessarily for upgrades, particularly if a newer system will not run on an older piece of hardware.]
You need El Capitan (10.11) at least which is an upgrade that is available, though I don't know which exact model MacBook Pro you have.
How to get old versions of macOS - https://support.apple.com/HT211683
- This link also has links to system requirements for each OS version which you should check against your exact computer model. Also make sure you have more RAM than what is noted as "minimum" for any particular system or your computer may run slowly.
- You may find you need to use Safari to get the download links to open in the Mac App Store application.
Back up your data in case something goes wrong --> Back up your Mac with Time Machine - https://support.apple.com/HT201250
or use a cloning tool.
Check if your old apps will still work with with the OS you want to install - https://roaringapps.com/apps
If you cannot upgrade your OS to the required 10.11 you can still use iCloud to do backups.
