You might find it unnecessary to have the entire product description to be part of QuickBooks and may want to use the product name itself instead of the description. Under Product Setting, You can specify your choice in this setting.
If you choose Yes, the description of the product in QuickBooks Online is filled with the Product Name in your Items list in Shopify.
If you choose No, the description of the product in QuickBooks Online is filled with the Product Description in your Items list Shopify.