In Sales Analytics on the Profit Overview page you will see your units sold for the selected timeframe and product or company level.
Here are what each of the categories under Units sold encompass:
Units Shipped are regularly priced (non-promo) units that have shipped. Once a unit ships, Amazon sends us all the order details. This includes the sales price and all fees. Data for shipped units is actualized data right from Amazon.
Promo Rebates are any units that had a promotional price associated with them that have also shipped. This could be a deal you are running with a discount code using Launch, coupons you are running on the listing directly through Amazon or any other promotional discount associated with the order. Units that are in the Promo Rebates group can be either Shipped or Pending.
Pending Units are any unshipped orders, both regularly priced and promotional. Amazon does not give us data beyond the item and unit count for an order until it ships. Any data besides the unit count for pending units is an estimate until the order ships. Once the order ships, Amazon sends us all the actual data associated with the order and your account will update automatically as this happens.
For more information on how estimates for pending units work, check out: Pending Units, Estimating Tool and Updating your Sales Price