I'll try to explain what I think is happening:
You have a character set up with the proper nodes (An area, animated sprite, and collision shape) I'm assuming. The reason your getting an error is likely because you do not have a node named "AnimatedSprite" (has to be named exactly, including capitalized letters) as a child of your character. It could also be that you have the script assigned to the wrong node. The script should be attached to the Area2D node.
It's hard to say for sure what the problem is without more information, but that would be my guess. I would look at the nodes and make sure they're named exactly like the tutorial and see if that helps. If that doesn't fix it, please post the error and your code, then we'll can see what we can do from there :smile:
If I recall correctly @kidscancode wrote the tutorial, so maybe he'll be able to help?
A minor nitpick, but it appears no where in the tutorial does it mention that $node_name is the same as get_node("node_name"). This should probably be changed, as I imagine it's one of the factors that's leading to your confusion and it could lead to others being confused later down the road. (Not to mention it is short hand, meaning it should be used to shorten code and/or make writing code faster. In my opinion, beginners to Godot shouldn't be $ using until they're more familiar with the engine, as it's rather confusing and until you're writing larger Godot projects there is little reason to shorten the code (as it's going to be rather short anyway). All of that said, I have nothing against using $ in the tutorial, as long as what it does is explained)
