The "Commissions" tab assigns the correct commissions to your sales. This amount is the sales price minus the AffiliCon fee, VAT and affiliate commission. Here you can find more information about the commission table.
The numbers correspond to all positive commissions. If there are more returns than commissions in your account, only a "0" will appear in this chart and no negative amount.
The chart shows the commissions of affiliates and vendors. If you are an affiliate and a vendor at the same time, you will see both commissions mixed here.