auto_update post title

hey,I’m new to wordpress, i need help

I have create acf field type list, and i want replace or auto_update the title of my post type (product) with value of field acf when i save automatically .

something like that:

function my_post_title_updater($post_id) {

    if ( get_post_type() == 'product' ) {
      $my_post['post_title'] = get_field('name_field');

    }
    // Update the post into the database
    wp_update_post( $my_post );

  }