A Manifest relationship indicates that the Artifact source embodies the target model element, typically in Component and Deployment diagrams. Stereotypes can be added to Enterprise Architect to classify the type of manifestation of the model element.
OMG UML Specification:
The OMG Unified Modeling Language specification, (v2.5.1, p.657) states:
An Artifact may embody, or manifest, a number of model elements. The Artifact owns the Manifestations, each representing the utilization of some PackageableElement. Profiles may extend the Manifestation relationship to indicate particular forms of embodiment. For example, «tool generated» and «custom code» might be two Manifestations for different Classes embodied in an Artifact.