Generally, you would only enter withholdings in the Other Federal Withholdings section of your account if you had withholdings on a form (like a 1099-MISC) that you were not able to enter elsewhere in the program. For example, you would report an amount here if you have an amount listed on the Form 1099-B, Box 4.
What impact does this entry have on my refund amount?
If you enter a withholding amount here that is already listed in the program, this will cause your return calculations to be incorrect. In turn, an incorrect entry for withholdings could result in the IRS adjusting your refund amount and delaying your refund.