Unlike an abstract that only provides a brief summary of an article or report, the phrase "full text" refers to an article or document in its entirety.
When you see the link to the full text or full text PDF within a database, you can click on that link to retrieve the full document. The full text PDF will display the entire document in its original format, including page numbers and graphics. (PDF stands for Portable Document Format.)
Many library databases provide links to the full text of articles and other documents; however, some index-only databases contain only the citation and abstract of the document but not the full text. These databases are still useful because you can read the abstract to determine if the document is relevant to your research topic and use the citation to track down the full text.