Fixed action patterns are basically actions that any is programmed to do. They aren’t really taught to do it but they just do it anyways.
An example of this is when a type of goose sees it’s eggs outside it’s nest it rolls them back in using it’s beak. However if you put something about the same size at the same place (e.g. a lightbulb) then the goose will roll that in as well. It doesn’t really know what it’s rolling in but just evolved that mechanism to keep it’s eggs from being outside the nest. (Read about it here).
To gain a good idea of how this works you should watch this video by Bozeman science.
Hope that helps 🙂