This tool is intended to show the tax treatment of distributions from a Roth IRA. (That is, it will show which amounts will be subject to ordinary income tax and/or 10% penalty.) Please note that it assumes that you are the original owner of the Roth IRA (i.e., you did not inherit it from somebody else).
Please see this article for a more thorough explanation of the rules for distributions from a Roth IRA: