Need to open or export Microsoft Office docs in macOS Sierra, but don’t want to spring for Office? You can use Pages, Numbers, and Keynote to open and save docs created with Microsoft Office.
Open Microsoft Word documents with Pages. Open Microsoft Excel documents with Numbers. Open Microsoft PowerPoint presentations with Keynote.
That’s all there is to it. Pages, Numbers, and Keynote are available from the Mac App Store.
(This how-to is based on my experiences and info on Apple's support pages — where the images sometimes come from.)