There will be a taxable capital gain from the value of the property when you became a Canadian resident.
For example, you bought the property for $100,000. When you became a Canadian resident, the property was worth $200,000. You sold the property today for $250,000.
You will be subject to a capital gain of $50,000 ($250,000 - $200,000) based on the value when you become a Canadian resident, and the disposition of the asset. The appreciation from when you first bought the asset to when you became a Canadian resident is not taxable in Canada. Note that when you become a resident of Canada, in some countries (depending on tax laws and treaties) there might be a deemed disposition whereby you would pay tax on any appreciation of the assets as if you sold it.