What do the words and figures on this foreign exchange bill stand for respectively? How to operate?

1 1906.50 represents the current commodity exchange rate, and selling at the market price means shorting, that is, buying down; 1 19 13.50 is higher than the market price, that is, if the current price is11913.50; Why are the two prices different? The difference between the purchase price and the seller is 7, which is the so-called difference, that is, the platform charges, and each platform is almost the same; Then you may think, isn't it more cost-effective to buy it like this? No need to deduct the difference? You are wrong. When you short (buy down) your position, you need to buy. Is your closing price the market price, or is it a bit poor? . . . . . Is there anything unclear to ask