You will receive a Form 1099-R reporting the retirement-account distributions paid to you. You must report the Form 1099-R on your tax return and the taxable amount will be included in your income.
(I assume that you have notified the custodian or administrator of your father's death, which you must do, and the payments made after your father's death are being paid to you, not to your father. As beneficiary, the retirement account became maintained for your benefit immediately upon his death.)
