Kubernetes namespaces provide organization and structure to clusters, allowing teams or projects to work in virtual clusters without impacting each other's work, improving manageability, performance, and security. A namespace strategy depends on factors like team size, project complexity, and scalability needs, with multiple namespaces needed for large companies or complex projects to isolate resources and ensure access controls. Creating a new Kubernetes namespace is done using the `kubectl create namespace` command or a YAML configuration file, and can be used to allocate costs, track resource usage, and separate development, testing, and deployment phases, offering improved security, role-based access controls, and cloud resource control.