To better understand this function you should execute this code first :
<?php
session_save_path('Your Path here !');
session_start();
$_SESSION['Key'] = 'value' ;
Var_dump(session_status() == PHP_SESSION_ACTIVE);
?>
Then you should execute this code :
<?php
session_save_path('Your path here');
session_start();
session_abort();
var_dump(session_status()== PHP_SESSION_ACTIVE);
?>
So if you have an open session , session_abort() will simply close it without effecting the external session data , so you can reload your data again from your path that you chose .