To import large amounts of Posts and Pages and related contents efficiently into WordPress using the Ultimate CSV Importer plugin, follow these steps: 

Step 1: Install and activate the plugin

1. Log in to WordPress: Go to your WordPress dashboard.
2. Search and install the plugin:
   • Go to Plugins > Add New.
   • In the search box, type Ultimate CSV Importer Free.
   • Find the plugin and click Install Now.
   • Once installed, click Activate.

Step 2: Prepare your CSV file

1. Create a CSV file: Make sure your file has the necessary columns for the data you want to import (e.g., post title, content, categories, etc.).
2. Ensure correct format: Check the plugin documentation for the correct formatting of fields and headers in the CSV file.

Step 3: Access the Ultimate CSV Importer Free plugin

The commercial and licensed version provides more advanced features.

1. Open the plugin:
   • After activation, find Ultimate CSV Importer Free in the sidebar of your WordPress dashboard (under Plugins or as a separate item).
2. Click "Import": Go to the Import tab, where you’ll be able to upload and import your CSV file.

Step 4: Upload Your CSV File

1. Click "Upload CSV": Browse and upload the CSV file from your computer.
2. Select Post Type: Choose the post type for your content, such as Posts, Pages, or Custom Post Types (e.g., WooCommerce products).
3. Map CSV Fields: The plugin will prompt you to map your CSV fields to the corresponding WordPress fields (e.g., map "post_title" to "Title" and "post_content" to "Content").
   • Note: Make sure to match each CSV column to its respective WordPress field.

Step 5: Import and verify

1. Import the data:
   • After mapping, click Proceed or Start Import.
   • The plugin will start importing the CSV content into WordPress.
2. View Import Summary: Once the process is complete, a summary report will show you how many posts were successfully imported, along with any errors (as shown in the image you provided).
   • You can also download detailed logs for verification.

Step 6: Check your imported Posts and Pages and related contents

1. View Imported Posts: After the import, navigate to the Posts or Pages section to verify that the content was imported correctly.
2. Edit as Needed: You can click on individual posts to ensure the data is correct and edit if needed.

Additional Tips:

• Field Mapping: Make sure to map CSV fields properly to avoid issues with missing data.
• CSV Format: Ensure that your CSV is properly formatted, with no special characters or extra spaces.
• Post Meta Import: If you are importing custom fields (post meta), map them to the appropriate WordPress meta fields.