This "proof" will attempt to show that all people in Canada are the same age, by showing by induction that the following statement (which we'll call "S(n)" for short) is true for all natural numbers n:
Statement S(n): In any group of n people, everyone in that group has the same age.
The conclusion follows from that statement by letting n be the the number of people in Canada.
If you're a little shaky on the principle of induction (which this proof uses), there's a brief summary of it below.