It means that we’re planning to make a kind of trading buffer of popular coins on our account. You will not need to wait for transactions, network’s confirmations - you just place a coin sale order on the exchange. In fact, there are our coins from our buffer in your locked order. As soon as your order works out, coins are automatically transfered from your staking balance and replenish the sold ones kept in the buffer. However, service’s commission for this option will be pretty high.