Security is a layered operating discipline, not a single plugin or product.
Start with access control: strong credentials, least privilege, multi-factor authentication where available and a documented recovery path.
Keep software current and remove unused components. Use monitoring and scanning appropriate to the platform, and make sure SSL/TLS certificates do not silently expire.
Backups are part of security because prevention is never perfect. Critical sites should have a recovery plan and, where practical, restore verification.