j is not pronounced like a y in Chinese.

https://forvo.com/search/%E5%8A%A0%E6%8B%BF%E5%A4%A7%E4%BA%BA/

So it is more like "Oh, Jianada!"in Mandarin and in Cantonese "Oh, Kanada!"

"ta bu shi jianada ren"

哈哈

Some countries names use it, while most do not. Unfortunately, there is no trick or pattern... we have to learn them as we go.

Here is a link if you'd like to browse a long list:
https://www.freechineselessons.com/country-names/

Sometimes the individual characters don't contribute to the meaning, they're just phonetic.

You could simply click on the word to see the hints.

In Cantonese, the first character is pronounced "ka", so the sounds are "ka na da" do you get it now? Mandarin, though, pronounces the first character as "jia", so that kind of ruins it a bit.

加拿大=Canada 加拿大人=Canadian (person)

She is not Canada vs She is not Canadian.