A Registered Retirement Savings Plan (RRSP) is a savings plan, registered with the Canadian federal government that you can contribute to for retirement purposes. When you contribute money to a RRSP, your funds are "tax-advantaged", meaning that they're exempt from being taxed in the year you make the contribution.

When it’s time to take your money out, you’ll pay taxes on the withdrawal amount, but likely at a much lower rate than what you’d pay today.

(https://www.sunlife.ca/en/investments/rrsp/)