The items on the bank reconciliation that will require a journal entry are the items noted as "adjustments to books." These items did appear on the bank statement, but they did not appear on the company's books.
A common example of a bank reconciliation item that will require a journal entry is the bank service charge. The bank service charge is often shown on the last day of the bank statement. Since it is on the bank statement, but not yet on the company's books, you will need to credit Cash and to debit an expense such as Bank Charges or Miscellaneous Expense.
Other examples of items that are on the bank statement, but not yet on the books include check printing charges, fees for returned checks, correction by the bank for errors in the company's deposits, collections made by the bank of the company's notes receivable, interest earned on bank accounts, miscellaneous bank fees, loan payments and other automatic withdrawals from the bank account.
If the bank made an error on the bank statement, you need to notify the bank so that the bank can make a correcting entry.