The conversion tool produced a bad-structured document.
It created sections where obviously you needed tables (bi-lingual dictionary if I guess correctly), where you can vertically “synchronise” terms between the columns.
It used Text boxes (drawing objects, not text) for your white-on-black “headings”. This may be valid under Word but wrong under Writer because it prevents you from styling nicely the corresponding text.
The tool also erroneously decided to style Heading n paragraph which are not headings. And, worst, direct formatting appeared nearly everywhere.
And, every page ended up as a style of its own with hard page breaks in between. Consequently your text does not flow smoothly from one page to the next but is jailed inside one (with the unfriendly effect of creating a new nearly empty page if you extend text and it overflows).
My best advice is: restart from scratch by pasting unformatted text into a new document. This should be easy now that you have useable text already collected in paragraphs (instead of simple lines as would be in a PDF).