why do speak english or french if you want to immigrate to canada

I think that's because canada has a province named quebec

It really depends on what area of canada you are going to be visiting, and whether you are going there to learn the culture, conduct business etc. Except for the province of Quebec (who only uses french), both languages (at the same time) are used on road signs, etc...and you will find that many/most people are fluent in both.

bcz both them are official language in Cnd