<?php
$banners = array ();
$banners[] = '1';
$banners[] = '2';
$banners[] = '3';
$banners[] = '4';
$banners[] = '5';
$banners[] = '6';
$banners[] = '7';
$banners[] = '8';
$banners[] = '9';
$banners[] = '10';

$banners = array_unique($banners);
$banners = array_rand($banners, 5);
   foreach ($banners as $k){
      echo $k;
   }
?>
 

<?php
header('Content-Type: text/html; charset=utf-8');
$banners = array(
"Один"=>1,
"Два"=>2,
"Три"=>3,
"Четыре"=>4,
"Пять"=>5,
"Шесть"=>6,
"Семь"=>7,
"Восемь"=>8,
"Девять"=>9,
"Десять"=>10
);
$banners = array_rand($banners, 5);
$banners = array_unique($banners);
foreach ($banners as $k=>$v){
   echo $v." ";
}
?>