The diagram shows a work package, which is a grouping of behavior and/or structure elements that can be assigned to one or more performers. A work package can be used to model a project or a program, and it can contain deliverables, which are outcomes of the work package. The four elements (A, B, C, and D) are all deliverables that are part of the work package.
References: ArchiMate 3.2 Specification, Chapter 10: Motivation Elements, Section 10.4 Work Package1; Chapter 11: Strategy Elements, Section 11.5 Deliverable2.