Great question! Shopify usually calls these ‘Options’ and ‘Values’ when they process an order. So the item might be a T-Shirt, and ‘Option 1’ might be ‘Size’ with the value ‘M’. So when you go to map the fields in Orderimp you should be able to get them to import using those ‘Option’ fields mapped to a column in your csv file that hold those values.
Here's a helpful article from Shopify on this: https://community.shopify.com/c/Shopify-Discussion/Correct-format-for-importing-products-with-variants/td-p/286027