Hello
In core/client.yml transifex resource appears the key js.email_login.link_label that said:
Email me a magic link
All right., I guess that refers to the link that the system generates automatically to enter, isn’t that? 
Para aquellos que hablamos español 
… no me queda claro si poner: “Enviarme el enlace mágico” para esta traducción.
This is a new feature which will be visible on login screen ( if the site setting for email login is enabled).
It basically let you request a mail with a link inside, that will log you in when you click it.
I think that “email me a login link” is probably better than a “magic” link, in any language.
Edit: Not that I don’t like magic.
Agree with @pfaffman here we should rename (both the translation and text) to “login link” it is far clearer.