Export a product set, filter by Category or all products.  Export all columns or choose specific columns such as price.  Always include the ID column to update existing products!

1. Prepare your CSV file. Your CSV only needs to include the column(s) necessary to identify the existing products (either Product ID or SKU) and the specific fields you want to update (e.g., price or regular_price).
2. Navigate to the Importer. From your WordPress admin panel, go to Products and click the Import button at the top of the page.
3. Upload your CSV. Select your prepared CSV file from your computer and click Continue.
4. Enable updates. On the next screen, make sure to check the box for "Update existing products". The importer uses the ID or SKU from your CSV to match and update the correct products in your shop.
5. Map the fields. WooCommerce will try to automatically match the columns in your CSV to the correct product data fields. Review these to ensure your "SKU" column is mapped to "SKU" and your "Price" or "Regular Price" column is mapped correctly to the corresponding price field. You can set any other columns in your CSV that you don't want to import or update to "Do not import".
6. Run the import. Click "Run the importer" to start the process. Do not close the window until the import is complete.