A release contains one or more applications. An application can be part of any number of releases.
Each release has a lifecycle, which specifies the phases for that release, such as a development phase, a testing phase, and a production delivery phase. For each of these phases, you specify one or more release environments, which represent the systems on which the applications are deployed during the phase. Also, each phase can have one or more phase approvals, which require a certain role approval before the application can move to the next phase.
Optionally you can add a process checklist to the release. Process checklists consist of milestones. For example, you can use milestones to track items such as cross-team kick off meetings, or tasks that must be completed by a certain date.