NJ Return - Pension, Annuities, & IRA Withdrawals Worksheet

I am hung up on the wording in Section 1 - IRA Withdrawals, Part B, Line 6: "Taxable contributions" made to IRA during current tax year.

 

I made $7000 non-deductible contribution to T-IRA in 2019.  Non-deductible, so contribution was made using taxed dollars.  Line 6 wording of "taxable contributions' is confusing.  At what point are they considering the contribution taxable?  At time of contribution (i.e. a nondeductible contribution has been taxed) or later when withdrawn (a deductible contribution will be taxed at withdrawal)?  Is my $7000 nondeductible contribution considered a "taxable contribution?"  TIA for clarifying.