How to create custom shortcode in WordPress?

function theme_name_movies_shortcode($atts = [])
{
$a = shortcode_atts( array(
    'no_of_posts' => 5,
    'title' => "Movies List"
), $atts );
 
$the_query = new WP_Query( array(
    'post_type' => 'movies',
    'posts_per_page' => $a['no_of_posts'],
));
if ( $the_query->have_posts() ) : ?>
    <h2><?php echo $a['title']?></h2>
  <ul>
   <?php while ( $the_query->have_posts() ) : $the_query->the_post(); ?>
       <li><a href="<?php echo get_permalink($the_query->ID)?>"><?php the_title(); ?></a></li>
   <?php
   endwhile;
    ?>
  </ul>
   <?php wp_reset_postdata();
else :
    __('No Movies');
endif;
 
}
add_shortcode(“movies_list”, “theme_name_movies_shortcode”);

// Use shortcode in a PHP file. 
echo do_shortcode( '[movies_list no_of_posts="5" title="Movies"]' ); 

[movies_list no_of_posts="5" title="Latest Films"]