Hi,
Well, first, you can just click on the "export" button of the products listing in your backend. It will give you a CSV with all the product data, including the columns product_code, product_name and product_quantity. So you can just ignore the other columns.
Now to get a CSV of all the products with just the columns you want, it's possible too. You need to create a mass action with the action "export a CSV file" and select the columns you want. You also need to increase the 500 elements limitation based on the number of products / variants you have.