In order to export coupons from WooCommerce, you will need to first login to your WordPress site. Once logged in, hover over the WooCommerce tab in the left-hand sidebar and click on Coupons. On the resulting page, you will see a list of all the coupons that have been created for your store.
To export these coupons, simply click on the Export button at the top of the page. A popup window will appear asking you to choose the file format and fields that you would like to include in the export. Once you have made your selections, click on the Export button again and your file will begin downloading.