For Balance Sheet accounts, the c/f figure is the amount to be shown in the Balance Sheet. Generally, a Dr balance is an asset, a Cr balance is a liability. At the start of the next period, this is the new b/f amount (the opening balance).
For Profit & Loss accounts, the c/f will be the amount transferred to the Profit & Loss account - a Dr balance is an expense, a Cr balance is income. At the year-end all Profit & Loss balances are transferred to the Profit & Loss account as follows:
Note that this adjustment should only be done after the period-end trial balance has been extracted (the trial balance must include the balance for every Profit & Loss item before transfer to the Profit & Loss account).