A single Kafka server is called a Kafka Broker. The Kafka Broker is the container of topics, it holds several topics with their multiple partitions. Each broker is a separate process that runs on a different machine and communicates with other brokers through a network.
A cluster can have multiple brockers and each broker is identified by a unique numeric ID and the brocker contains certain topic partitions. All the topic partitions data is Distributed across all brokers(load balanced).
In the next topic, you will understand about
Kafka Topics