If you type "http://www.yoursite.com/wp-includes/" in your Internet Browser, you will see the list of directories and its files as shown in the following figure:
In this case, you can disable Directory Browsing to protect your content from hackers who might be able to misuse it.
To disable the Directory Browsing feature, please add the following line at the bottom of the .htaccess file.
# Disable Directory Browsing Options All -Indexes
Now you will not see the content of the directories when you try to access them. When you try to access the /wp-includes/ folder, 404 Page Not Found error page appears, or the following message will appear:
Access Denied
Or
Forbidden You don't have permission to access /wp-content/uploads/ on this server.
For your reference, disabling the Directory Browsing feature will not affect SEO of your site.