FormattableMarkup : Add parameters, links to a text, table cell data.

Create a customizable text.

Example :

use Drupal\Component\Render\FormattableMarkup;

$text = new FormattableMarkup('My name is @name', ['@name' => "The name"]);

Theme table row to link particular column data.

Example:

use Drupal\Component\Render\FormattableMarkup;

$rows[] = [

'data' => [

  'name' => new FormattableMarkup('<a href=":link">@name</a>', [':link' => $url, '@name' => $name]),

  'mail' => $row->mail,

]];