Hyphenation is splitting a word or some words which the length is/are not fit the end of line. Every word processor can do hyphenation. Hyphenation done based on the language of the text. Hyphenation in a text document is best in Justified arrangement (not Center nor Left nor Right). Here, we want to introduce how hyphenation for English (US) done in LibreOffice Writer. We use LibreOffice 126.96.36.199 in Ubuntu 16.04.
You can do hyphenation by choosing a paragraph or some paragraphs and click menu Tools > Language > Hyphenation.
This will make a Hyphenation dialog appears. It asks you to accept every suitable hyphenation found in your paragraph(s) selection. You may choose Hyphenate to do hyphenating one by one, or choose Hyphenate All to do it automatically. If you do choose Hyphenate, you may change the splitting manually.
As the result, you may see this paragraph example. See the right edge where the words con- and re- splitted from nection and quest.
you can do hyphenation by choosing a paragraph or many, and do click menu Format > Paragraph > Text Flow > enable Hyphenation: Automatically. Its default configuration is basically safe.
As the result, you may see this same paragraph.