Ok, let me explain that to you.
In the editor click on Edit->Project Settings and then click input on the left side.
There you can map your input.
Action Mapping is for command-like input (Jump, Shoot,…)
Axis Input is for smoother input like walking, turning, etc.
You can assign a key to a command name and bind the events to a function in SetupPlayerInputComponent function in your Pawn / Character subclass.
There you can use W and S with your CharacterMovementComponent to walk, and A and D with a yaw rotation to turn around. You can find all that below.
If you are a complete starter or want a complete tutorial with examples, look here it helped me a lot:
Greetings