X-Pack security enables you to easily secure a cluster. With security, you can password-protect your data as well as implement more advanced security measures such as encrypting communications, role-based access control, IP filtering, and auditing. For more information, see Securing Elasticsearch and Kibana and Configuring Security in Kibana.
You can create and manage users on the Management / Security / Users page. You can also change their passwords and roles. For more information about authentication and built-in users, see Setting Up User Authentication.
For a more holistic overview of configuring roles for the entire stack, see Configuring Role-based Access Control.