What is "full-text"?
Think of the database as an electronic filing cabinet full of records. For every item (e.g., article, book) indexed by the database, a record has been created. (We call this a surrogate, because the record represents the item but it isn't the actual item.) This record provides a lot information about the item (title, author, year of publication, etc.). Sometimes, the database contains a record for an item that exists, but not the item itself. These items, if desired, must be requested through interlibrary loan. However, when the database also contains a record accompanied by the actual item it represents, then this is considered a full-text item. In a nutshell: when you limit your search to full-text, this means you'll be able to read all the items in your result list.
How do I find full-text items?
When you conduct your initial search, look for a check-box that says full-text.