Your RRSP deduction limit is the amount that you can contribute to your (or your spouse's) RRSP, PRPP (in addition to your employer's contributions), or SPP. It's also the maximum amount of these contributions you can deduct on your tax return, reducing your tax for that year.
If you didn't make any contributions, then your RRSP deduction limit will likely not affect your tax return.
This CRA page has more info on the RRSP deduction limit: https://www.canada.ca/en/revenue-agency/services/tax/individuals/topics/rrsps-related-plans/contributing-a-rrsp-prpp/contributions-affect-your-rrsp-prpp-deduction-limit.html#whtddctnlmt