I used title and it worked!
The title attribute gives the title of the link. With one exception, it is purely advisory. The value is text. The exception is for style sheet links, where the title attribute defines alternative style sheet sets.
<a class="navbar-brand" href="http://www.alberghierocastelnuovocilento.gov.it/sito/index.php" title="sito dell'Istituto Ancel Keys">A.K.</a>