Servos vary in the range of motion their arms have. For the angles, you make a request in your software to map correctly to the angles the servo actually moves in; you need to configure the servo with its actuation range. Once configured, you will be able to accurately move the arms connected to servos into their correct positions. This is an important step in configuring any project you plan to use servos in. If you don't do this, you will face a number of strange surprises where the servo arms keep moving to the wrong positions.
Setting the actuation range of a servo
Getting ready
You will need access to the REPL on the Circuit Playground Express to run the code presented in this recipe.