There are 2 different counts of items in Sellbrite, and they depend on which page you're on.
The Product catalog counts the total number of rows that are presented in front of you. Since we do not include variations in the Catalog view, a Product with variations is counted as 1, no matter how many variations you have.
So if you had 5 single products, and one product with 5 variants, it would count 6.
The reason we do this is to make it easier to navigate the Products page, as well as more efficient to list products with variations in bulk.
The Inventory Manager view (accessible from the Products page) counts ALL inventory items, so in the scenario above, it would count 10.
The Dashboard also counts all inventory items, so the count would be 10.
The reason for the Dashboard inventory count is to let you know what percentage of your inventory items are listed on each channel.
If you wish to see your SKU count as it relates to your current Subscription Plan, you can always check the counter on the Your Subscription page, in Settings.