how to catch a data from a array in WordPress

The “array” you show in your screenshot is an array of WP_Post objects (well, in this case it’s an array of 1 WP_Post).

In this specific case, you can get the page’s information like this:

var_dump( $page_details[0]->post_title );

…which will get the post_title property from the zeroth (first) (well, only) WP_Post object in your array.

In the case where you’ve got more than one WP_Post in the array, you can get all their titles like this:

foreach ( $page_details as $page ) {
    var_dump( $page->post_title );
}