Well basically it takes an array and stores it as a string. You can place the string in the database and then unserialize it back into an array once you've pulled it back out the database. vB3 uses it in a lot of places so it's a good idea to read up a bit on how it works
Just write a test script:
PHP Code:
$array = array('yes', 'no', 'why', 'word');
$temp = serialize($array);
echo $temp;
$temp = unserialize($temp);
print_r($temp);