An ISO is a disc image. Because Office 2013 predates the "click-to-run" streaming installer (modern ODT), the VL version was distributed as a static ISO for installation via DVD or USB.
The file is the Portuguese (pt-PT) volume license (VL) version of Microsoft Office Professional Plus 2013 for 64-bit systems. This specific edition is designed for businesses and organizations that manage their software licenses in bulk rather than through individual retail keys. Key Specifications and Features Install Microsoft Office Professional Plus 2013 pt office professional plus 2013 x64 vl.iso
pt_office_professional_plus_2013_with_sp1_x86_and_x64_dvd_3921865.iso Third-party sites : Sites such as Heidoc.net An ISO is a disc image