NullReferenceException was thrown. Object reference not set to an instance of an object.

Hello! So, I am extremely new to Unity and do not know much. Here is a screenshot of what I have so far. Nothing complicated at all, just movement.

Does anyone know how to fix this? PS: Please use basic language, by reading other comments, I do not understand much because of such complex vocabulary. Thank you!!

Try to change “void start()” to “void Start()”