How get a value from a plugin into another plugin through action/filter

when the shortlink is created, an action is trown with this line :

do_action('fts_use_shortlink', $post_id, $shortlink);

then you can hook your code on the action with this code e.g. in the 2nd plugin :

add_action("fts_use_shortlink", function ($post_id, $shortlink) {

    // here you can use $shortlink


}, 10, 2);
// 10 is the priority when there is several hooks
// 2 is here for the 2 arguments $post_id and $shortlink