The easiest way to see your available trading balance once you are logged into your kraken account is by navigating to Kraken Pro.
Once you navigate to Kraken Pro select a pair that includes a currency you'd like to check available balances for.
Using the buy and sell buttons you can check the base or quote currency funds available by looking at the small bar in the Funds field. Hovering over this bar will give you the exact funds that are currently accessible.
Another way to see your available balance for a specific currency on Kraken.com is by looking at the "withheld" amounts on the withdrawal page for that currency in the funding section of your kraken account.
For example, if you want to buy a cryptocurrency using EUR, you can go to Funding > Withdraw > EUR and look at your "withheld" amount. Your "withheld" amount is usually the amount you have tied up in open orders, so that number subtracted from your balance in EUR will tell you how much EUR you have left for new orders.
If your balance in EUR is less than your verification level's withdrawal limit, then the figure listed as your "maximum withdrawal" amount will be the same as the amount of funds you have left for new orders.
The same goes for other currencies - you can look under Funding > Withdraw > [currency] to see how much is withheld in that currency.