Ambiguous description of _process() (#9084)

* Fix ambiguous description of _process()

getting_started/first_3d_game/03.player_movement_code.rst

@@ -119,10 +119,9 @@ using the global ``Input`` object, in ``_physics_process()``.
         }
     }
 
-Here, we're going to make all calculations using the ``_physics_process()``
-virtual function. Like ``_process()``, it allows you to update the node every
-frame, but it's designed specifically for physics-related code like moving a
-kinematic or rigid body.
+Here, instead of ``_process()``, we're going to make all calculations using the ``_physics_process()``
+virtual function. It's designed specifically for physics-related code like moving a
+kinematic or rigid body. It updates the node using fixed time intervals.
 
 .. seealso::