Your online store may be using dynamic URLs with "GET" parameters (like cart.php?target=category&category_id=2) if it failed to enable human-readable URLs during the installation. To achieve better visibility in search results, it's recommended to configure SEO-friendly or clean URLs, as they are called in X-Cart.
Ensure you configured the server to support SEO-friendly URLs. See more info about server setup here.
To be able to use Clean URLs in your store, make sure you enabled the "Enable clean URL" toggle on the SEO Settings page of your store Admin area (Store Setup -> SEO Settings):
If you are using X-Cart 5.3.1 or earlier, go to the System Settings > Environment section and look for the "Enable clean URL" button halfway through to the page bottom.
When enabled, your store should start using SEO-friendly URLs, and after a couple of seconds, you should see a success message at the top of the page saying, "Clean URLs are enabled."
If your server environment is not compatible with handling redirects properly and thus is not able to work with SEO-friendly URLs right now, you will see the following message:
If this is the case for your store site, you will need to set up your server properly before you can use SEO-friendly URLs. You may require a different setup depending on your server software. This article provides guidelines for how you can do a Clean URLs-related server setup on Apache, IIS, and Nginx.