Once you have deposited funds into your account or placed a trade, your account balance will change. Leverage allows you to trade with more capital than your original equity investment.
You can see your latest account balance information in the top left panel.
Let's take a look at each field:
Buying Power: total available buying power to increase your position. Your buying power will change based on the market you have selected. This is based on the amount of leverage available in each market.
Equity: total value of your account.
Margin Usage: percentage of your total margin used by open positions.
Account Leverage: leverage of your account based on all your open positions. Because your account is cross-margined, each open position has its own leverage while also affecting your overall account leverage.
How does Cross-Margining work on Perpetuals? https://help.dydx.exchange/en/articles/4797405-how-does-cross-margining-work-on-perpetuals
Maximum Leverage for Perpetuals https://help.dydx.exchange/en/articles/4797403-maximum-leverage-for-perpetuals