Knows about is a property that links person entities to some other concept in the knowledge graph that can be in many different classification systems. It is used to turn text-only labels for things like expertise terms shared via staff profile pages to something in the knowledgebase with more definition and organization. Not all expertise terms are as yet linkable with more curation work needed to incorporate additional knowledge into the GeoKB and further work on refining embedding models to help link concepts more effectively. All expertise terms from staff profiles are recorded in the schema.org documents stashed in item talk pages for person entities, so those terms will still be useful in full text search on the Wikibase while we work to get them refined into the system.