The term document refers to a single page or item in a website search index. On a publishing website, for example, a document could be a single article. On an ecommerce website, a document could be a product listing. SERPs list documents that are relevant to a given query, sorted by their relevance score. The structure and format of documents in a search index is called the schema.
In the Content tab of your Swiftype dashboard, you can view and edit all the documents in your search engine index. In this tab, you also can individually add or delete documents from your search engine index. Under the details tab for a specific document, you can also view the various fields and overall schema of an individual document.