There are two ways you can find out the length: Draw a right triangle with the two ordered pairs and find the hypotenuse of it using Pythagorean theorem or use the distance formula. I'm going to use the latter.
Distance formula = where (X1, Y1) is the first ordered pair listed and (X2, Y2) is the second.
Now, just plug in and solve.
Your distance between the two points is √205 units or ≈ 14.32 units