In the bottom bar, in the document, you have 4 possibilities for outputing the document: Print, E-mail, PDF and Preview.
Print: Prints the current document.
E-mail: A PDF file is sent throught Mail.app or Invoy.
PDF: Saves a PDF of the current document.
Preview: Opens Preview.app and makes a preview of the document.
Warning: Print, E-mail and PDF are disabled if the document is a draft, these buttons will be enabled after finalizing the document
CSV: CSV allows your data to be opened in a spreadsheet application (like Excel or Numbers).
SAFT: This format is required by some countries, for audit purposes ¹.
¹ Currently, only the Portuguese format (SAFT-PT) is available.