What do think about Meta4 and exposure?
In this picture, it's easy :
Volume is the position(s) volume including leverage. Negative value indicates the sell of the currency. A standard lot is 100,000 units. So -10,000 indicates a SELL of 0.1 EUR against something. It can only be USD in this case. Same for GBP.
USD columns is the value of the asset in account currency (here USD). 10,000 EUR at 1.26236 give you 12,623 USD. To get 31,56 you have to divide by 400, it's the leverage.
EDIT: How to use these information in trading is an other matter. I really don't know