A Package Import relationship is drawn from a source Package to a Package whose contents are to be imported. Private members of a target Package cannot be imported. The relationship is typically used in a Package diagram.
OMG UML Specification:
The OMG Unified Modeling Language specification, (v2.5.1, pp.28-29) states:
A PackageImport is a DirectedRelationship between an importing Namespace and a Package, indicating that the importing Namespace adds the names of the members of the Package to its own Namespace. Conceptually, a Package import is equivalent to having an ElementImport to each individual member of the imported Namespace, unless there is a separately-defined ElementImport. If there is an ElementImport for an Element, then this takes precedence over a potential import of the same Element via a PackageImport.