functions.php

function count_post_visits() {
   if( is_single() ) {
      global $post;
      $views = get_post_meta( $post->ID, 'my_post_viewed', true );
      if( $views == '' ) {
         update_post_meta( $post->ID, 'my_post_viewed', '1' );   
      } else {
         $views_no = intval( $views );
         update_post_meta( $post->ID, 'my_post_viewed', ++$views_no );
      }
   }
}
add_action( 'wp_head', 'count_post_visits' );

add this anywhere in your template where you wish to display the posts.

<?php
$popular_posts_args = array(
   'posts_per_page' => 3,
   'meta_key' => 'my_post_viewed',
   'orderby' => 'meta_value_num',
   'order'=> 'DESC'
);
 
$popular_posts_loop = new WP_Query( $popular_posts_args );
 
while( $popular_posts_loop->have_posts() ):
   $popular_posts_loop->the_post();
   // Loop continues
endwhile;
wp_reset_query();
?>