She can open a TFSA at any discount brokerage (e.g. questrade, rbc direct, etc…) and invest in stocks, bonds, options, mutual funds, etfs, etc… from within the TFSA. Gains are not taxed, but losses can't be claimed against income.
Anyone looking for "growth" in this economy is going to have to accept a high level of risk, so your sister should be prepared for the possibility of losing a lot of money if her investments (and the market as a whole) tank.