BOSH is an open source tool for release engineering, deployment, lifecycle management, and monitoring of distributed systems. It handles packaging, infrastructure provisioning across multiple clouds, application deployment with features like canary releases and rolling updates, configuration management of services rather than individual servers, and monitoring of processes, nodes, and the overall service. The presentation demonstrated deploying an ELK stack on AWS using BOSH and showed how it can scale the deployment vertically, horizontally, add more disk space, replace nodes, and add monitoring.