Balance
This is the value of your account before considering any current open positions.
Equity
This would be the current value of your account if all current positions were closed.
Margin
This is the amount of money you need to have, and maintain, in your account to cover any open positions.
Free Margin
This is the difference between your Equity and the Margin amount above.
Margin Level
This is the ratio of Equity to Margin, calculated by the following formula:
(Equity / Margin) x 100 = Margin Level