Azure Service Bus can be used for queueing and messaging between applications. It provides entities like queues, topics, and subscriptions that applications can use to exchange messages. Key capabilities include brokered messages up to 1MB in size, various receive modes like peek lock that provide at-least-once delivery, and features like auto-forwarding, dead-lettering, scheduling, transactions, and filtering that help manage messages and ensure reliability. While powerful, Service Bus also requires understanding various concepts like duplicate detection, ephemeral entities, and FIFO to effectively implement messaging solutions at scale.