The Canadian dollar is a commodity-currency tied closely to crude oil, since energy is Canada's largest export and the United States its dominant customer. When oil rallies, USD/CAD usually falls, meaning the loonie strengthens.
Note the quoting direction trips people up: USD/CAD rising means the Canadian dollar weakening, because the pair is quoted with the US dollar as base. Canadian data and Bank of Canada decisions move it, but so does anything that moves cl.
Example: crude falls from $78 to $70, about 10%. USD/CAD rises from 1.3550 to 1.3720, a 170-pip move worth roughly CAD 1,700, or about USD 1,239, per standard-lot.
Related: currency-nickname, cl