Hi!
I understand that you're using the IRS Tax Withholding Estimator, and have a question as to Item 3. I'm a little unclear as to what the Item 3 you're referring to is, but I suggest that you restart the interactive estimator tool, as the questions are all in a specific order and adjust to the previous answers you've supplied.
As an alternative, you may want to try using TurboTax's W-4 Calculator, which may be clearer and easier to use.
If neither is helpful, feel free to post a follow-up question with some additional, specific details as to where the source of your question is coming up. We're happy to help. Thanks!