Assuming you’re connected to the internet, your Mac will check for any available system updates. Or, click the Apple menu icon on the menu bar and select “System Preferences.” You can also search for this option by pressing Command+Spacebar, then typing “software update” to in the Spotlight window that appears. Checking your Mac for viruses - wait, what? Macworld.
To make sure your Mac malware database is always up to date you'll want to verify that your Mac always automatically installs security updates and related system data files.