Right... Because you're not passing in how the date should be formatted.
The date() function is for formatting any timestamp any way that you want, so you need to tell it that you only want the date, month, and year, and how you want those represented.
The first parameter is the format string, and the second is the UNIX timestamp, which is just an integer measuring the number for seconds since 1970 or something.
Here are some examples from the date() function docs on php.net.
// Assuming today is: March 10th, 2001, 5:16:18 pm
$today = date("F j, Y, g:i a"); // March 10, 2001, 5:16 pm
$today = date("m.d.y"); // 03.10.01
$today = date("j, n, Y"); // 10, 3, 2001
$today = date("Ymd"); // 20010310
$today = date('h-i-s, j-m-y, it is w Day z '); // 05-16-17, 10-03-01, 1631 1618 6 Fripm01
$today = date('\i\t \i\s \t\h\e jS \d\a\y.'); // It is the 10th day.
$today = date("D M j G:i:s T Y"); // Sat Mar 10 15:16:08 MST 2001
$today = date('H:m:s \m \i\s\ \m\o\n\t\h'); // 17:03:17 m is month
$today = date("H:i:s"); // 17:16:17
?>
Just remember that when you call date(), instead of just passing it the format (like they do in the example) you'll also want to pass your timestamp variable, eg
date("j, n, Y", $myTimestampVariable);
