Stocks are constantly changing in price. When you see a price on the screen you see the last price that the stock was traded at. By looking at the last transaction you have a good idea what you would get if you bought/sold a stock now.
The number before it says how many where traded.
In your case the last trade made with that stock was for 900 shares and it sold for $6.15. $6.15 is really the only important number on the screen though.
