I've a website which is in
fr-FR and I'm building links for the
en version of the website.
Should I put all the
fr links on the English version
nofollow? Is it a good practice?
No, instead of that just use rel="alternate" tag, as the google documentation recommends:
<link rel="alternate" hreflang="es" href="https://example.com/es/my-page/" /> <link rel="alternate" hreflang="en" href="https://example.com/en/my-page/" />