Use method “get” or “post”
<form action="/action_page.php" method="post">
<h3>WHAT IS THE RETURN DATE?</h3><br>
<input type="date" name="hotel_name" value="">
<br>
</form>
And in the “action_page.php” you can use this code
$return_date = $_POST['hotel_name'] ;
In this way you can store the date in variable $return_date