Different tool, different terminology.
What M$ Word calls a section (break) is a change in page characteristics, such as header, footer, columns, …
In LO Writer, everything related to a page, such as margins, header, footer, base number of columns, … is stored in a page style. You need a special page break to change page style. Note that contrary to M$ Word, Writer changes happens after a page break and can’t be effective inside the middle of a page.
If you need a temporary change in number of columns or enlarging/shrinking margins (this additional space positive or negative is called an indent), without changing other parameters, this is done with a section which is immediately in effect (does not need a page break). A section resides inside a page (may extend on several pages though) and the rest of the layout/formatting is inherited from the page style.
To learn the details and find terminology definition, download and read the Writer Guide.
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