Capital loss carry over (short term or long term) is not applied directly against current year dividend income.
Your dividends will show on line 3b of form 1040. Your net capital gain or loss (after combining the capital loss carry over with any 2019 gains or losses on Schedule D) will show on line 6. If there is a loss on line 6, it will effectively reduce your total income, subject to tax, not just your dividend income.
