In databases, the information (e.g., the title, the author's name, the publication date, the subject headings) are put into fields. When searching, you can limit your search to specific fields.
In the example, the search is for an article on UX published by the Harvard Business Review. In the drop-down next to the search field with the publication name, the publication field has been selected. Had this field not been selected, the results would have included articles and other sources from other publications as well.
The design of this page was partly adapted from Research: By Course, Subject, or Topic, by University of Arizona Libraries, © 2020 The Arizona Board of Regents on behalf of The University of Arizona, licensed under a Creative Commons Attribution 4.0 International License.