Those are called "pull quotes"
Used to attract attention, especially in long articles, a pull-quote is a small selection of text pulled out and quoted in a larger typeface or using some other formatting distinct from the rest of the article. A pull-quote may be framed by rules, placed within the article, span multiple columns, or be placed in an empty column near the article.
It is also sometimes known as a call-out, but not all call-outs are pull-quotes.
There's no specific element in html5 for pull-quotes, you would likely code them as an
<aside> or a
<blockquote>, Semantically, they would likely be an
<aside>, since you should be able to remove them without the remaining content becoming incomplete.
Ideally you'd also code them so the content of the pull-quote doesn't appear as text in the content.