For explanation purposes I'll call Point A (14,-6) and Point B (12,8) the given points.
To calculate the distance between both points you have to calculate the distance between each coordinate over the x and y axis.
Then apply the Phytagoras theorem to calculate its length.
I'll sketch the points:
x-axis

y-axis

Now according to the Phythagoras theorem, the sum of the squared base and the squared heigth of a triangle is equal to the squared hypotenuse:

For this triangle:
![\begin{gathered} 2^2+14^2=c^2 \\ c^2=200 \\ c=\sqrt[]{200}=10\sqrt[]{2}=14.14 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/8iglyx7yup7n3apjvw35p8wufm847ccvud.png)
The distance between both points is 14.14 units.