Hey there, you only get charged capital gains if you sell a capital property for a realized gain. In this case, your capital property is a stock, so yes you only get charged capital gains tax if you sell it. You could be up 10,000% on a stock inside of a cash account. It doesn't mean anything until you sell.
We don't like to give tax advice, particularly because it ranges by province, and it's subject to change at any time. However I can tell you that you DON'T get charged the full amount at your personal rate. Capital gains tax is only for 50% of your capital gain. If you bought $1000 worth of stock and it tripled to $3000, you'd get charged capital gains tax on $1000.
Initial investment= $1000
Capital gain = $2000
Taxed on = $1000 (half of $2000)
Now, what that tax rate is varies by province, so I won't speak on it. You'll have to look it up, which should be fairly easy.
In terms of capital losses, here's a snippet right from the government of Canada:
"Generally, if you had an allowable capital loss in a year, you have to apply it against your taxable capital gains for that year. If you still have a loss, it becomes part of the computation of your current year net capital loss. You can use a current year net capital loss to reduce your taxable capital gains in any of the 3 preceding years or in any future year."
From what I understand, you cannot use capital losses against your income, you can only use them to offset capital gains. So if you have a capital loss, but don't have any capital gains that year, you can apply them to years prior (3 according to that statement) or any year moving forward.
Make sense?