Can someone please elaborate on the 'Payments with 2020 federal extension'? Is it for the actual 2020 taxes, or for the 2019 taxes for which I filed an extension in 2020?

The language is not clear in the instructions. I filed an extension for my 2019 taxes in 2020, and paid that tax due later in 2020. Does this mean that I can include this amount in the 'Payments with 2020 federal extension'? When it says '2020', I don't know if it means the 2020 taxes or the actual year 2020.