There are two types of trading commissions: fees (0.1%) and rebates (0.01%).
Fees are what you pay, and rebates are being paid to you.
The logic is as follows: you're paying when emptying the order book, and you're being paid when adding new lines to the order book.
For example, you're creating a market order. Being executed, it removes liquidity from the order book, fills other users' orders. The same thing happens when you're creating a limit order which already has a suitable pair in the order book. In that case, you're paying a 0.1% fee as your order is being executed.
If you're creating a buy limit order below the current price, or a sell order above the current price, your order is being added to the order book. You're increasing the liquidity, that's why you'll be paid a 0.01% rebate as your order is being executed.
Take a look at the picture. Fee and rebate are displayed right above the "Sell/Buy" button. And don't forget to learn more about how fees are calculated.