The CRA administers federal and most provincial income tax. Its most consequential judgment for active traders is characterisation: profits can be capital gains, of which only part is included in income, or fully taxable business income. Frequency, holding period, knowledge of markets, financing, and intention all feed that decision.
The same analysis drives the tfsa-day-trading-risk problem, where a tax-free account carrying on a securities business can be taxed on its profits. Canada also applies a superficial-loss-rule that resembles the US wash sale rule with different mechanics.
General information only, not tax advice. Inclusion rates, thresholds and CRA administrative positions change, and outcomes depend on your facts, so consult a Canadian tax professional.