Trying to complete my 2021 income tax return, its asking me about "State Tax Refund Worksheet: Item Q line 1", says should be entered, enter zero if none. Whats this for?

The worksheet is to determine if your State Refund (which was received in 2021) should be reported as taxable income on your 2021 Federal return. 

You can return to the Income section and revisit the interview for the 1099-G that reported your state tax refund. 

If you took the Standard Deduction on your 2020 federal return, the state refund is not taxable. 

If you itemized for 2020, Item Q line 1 on the worksheet is asking for what you reported on your 2020 Schedule A line 5b (State and local real estate tax/property tax paid in 2020)