It looks like you saved your Word document directly as an .html file and not as a filtered .html file, which is usually not a good idea.
You may want to check out the
e-Book Tools Word add-in created by MR member Toxaris, which'll clean up Word documents before export and also allows you to save your book as an .ePub file, which you can edit with Sigil and convert to a Kindle book with Kindle Previewer/KindleGen or Calibre.
(Direct HTML to Kindle conversion is only recommended for experienced Web designers who create their files in an editor from scratch.)