Pointing Scale
The point estimate for a story is between 0 and 3. These estimates are to assess 'risk' involved for the described task with 0 being the absolute lowest and 3 being the highest.
Here is how I generally describe each value:
0Copy changes, absolute no-brainer items1Straight-forward change, approach is known and comfortable to developer2Task is straight-forward with a small set of approaches available, but if first option does not work out another has to be tried3Task is unfamiliar and risky. If an idea does not pan out, it could be back to the drawing board to figure out other options.
As a general rule you want to avoid using estimates that are 0 except in the most simplistic cases as they will mess with overall team velocity and are a sign stories are too granular.