A per item or line item promotion is a discount that applies to qualifying line items.
All discounts deduct either a specific dollar amount or a percentage of the product or order depending on the configuration.
For an overview of all promotion capabilities in OroCommerce, watch this video: https://www.orocommerce.com/media-library/create-promotions
For more training videos, check out our media library here: https://www.orocommerce.com/media-library
line item promotions, per item promotions