Reference: https://docs.servicenow.com/bundle/rome-platform-administration/page/administer/import-sets
/reference/import-sets-landing-page.html

The Security Hardening feature in the ServiceNow Security Operations Security Center is specifically designed to help identify, resolve, and mitigate platform-related security issues and misconfigurations.
Security hardening provides prescriptive guidance on improving your platform's security posture by addressing vulnerabilities and ensuring compliance with security best practices. It includes automated checks and recommendations related to system configurations, access controls, and other settings that, if left unchecked, could expose the system to threats.
The Security Center's Security Hardening dashboard aggregates these findings and allows administrators to track remediation progress effectively. Unlike the Security Scanner, which focuses more on vulnerability scanning of integrated systems, or Customer Actions, which involves manual customer intervention for specific issues, Security Hardening is the proactive tool ServiceNow provides to manage platform security risks internally.
References:
ServiceNow System Administrator Study Guide, Security Operations Chapter ServiceNow Product Documentation, Security Operations > Security Center > Security Hardening ServiceNow Docs: Security Hardening