AccountingCoach.com has an Explanation of Debits and Credits. It also has Drills to help you understand debits and credits. There is also an Explanation of Chart of Accounts, which will tell you which accounts are balance sheet accounts and which are profit and loss accounts. The website is free.
In short, the revenue, gain, expense, and loss accounts are profit and loss accounts. The balance sheet accounts (cash, accounts receivable, land, accounts payable, owner's equity, etc.) are usually listed first in a company's general ledger and on the trial balance.