>A paragraph-ending line that falls at the beginning of the following page or column, thus separated from the rest of the text. Mnemonically, a widow is "alone at the top" (of the family tree but, in this case, of the page).
>Orphan
>A paragraph-opening line that appears by itself at the bottom of a page or column, thus separated from the rest of the text. Mnemonically, an orphan is "alone at the bottom" (of the family tree but, in this case, of the page).
>Alternately, a word, part of a word, or very short line that appears by itself at the end of a paragraph. Mnemonically still "alone at the bottom", just this time at the bottom of a paragraph. Orphans of this type give the impression of too much white space between paragraphs.
https://en.wikipedia.org/wiki/Widows_and_orphans
In this case the author is referring to the last definition, short lines at the end of a paragraph.