What's 1/3 x 6 ?

Well, that's 1/3 of 6. Think about it:

You have 6 pizzas...

one whole pizzaone whole pizzaone whole pizza
one whole pizzaone whole pizzaone whole pizza

and you get to eat 1/3 of them.

This is like splitting up the pizza between 3 people:

one whole pizza
one whole pizza

You get 2 pizzas

one whole pizza
one whole pizza

Your friend gets
2 pizzas

one whole pizza
one whole pizza

And your dog gets
2 pizzas

So 1/3 of 6 is 2.