Craft 3 doesn't translate static strings
I'm simply trying to follow the docs as good as possible.

Try the following:

Example String we'll be using: "cheese" | "fromage"


in your config/general.php make sure you have your siteUrl set as an array with at least two entries, example:'siteUrl' =&gt; ['my_site_en' =&gt; 'http://localhost:1234, 'my_site_fr =&gt; 'http://localhost:1234/fr/'];
in your translations/fr/site.php make sure it only contains the following

&lt;?php

return [
  'cheese' =&gt; 'fromage',
];

in your twig file add the following &lt;h1&gt;{{ "cheese"|t }}&lt;/h1&gt; 


4. important: Access your Control Panel (cpTrigger in config/general.php for the first part of the URL), => http://localhost:1234/%CP_TRIGGER%/settings/sites and make sure you have 2 sites, both in the same group, one in en, one in fr &amp; their URLs must also be set!   It should look similar to this 

As long as all 4 steps are followed, it should work.

Hope this helps!