A slight correction, en-dashes are used mostly to indicate ranges like Mon–Fri. Hyphens are a separate third thing, smaller than an en-dash.

- hyphen
– en-dash
— em-dash

They get their names originally from having the same width as the letter n or m respectively in typesetting (though not all fonts follow that necessarily).

“It is important, when killing a nun, to ensure that you bring an army of sufficient size. For Sister Thorn of the Sweet Mercy convent Lano Tacsis brought two hundred men.”

• Red Sister, Mark Lawrence.

Good book if you want something a bit like Harry Potter but aimed at a more mature audience and not funding the stripping away of human rights.