The meaning of "actions.actions" in CMD ["start", "--actions", "actions.actions"] for rasa-sdk dockerfile

In the last line of rasa-sdk Dockerfile, there is “actions.actions”. What does it mean?

I’m somehow confused about the location of, should I put it in an “actions” folder or outside of it? And also, where should I put the and some custom python package file, like, which is being used as from aaa import bbb in I tried to put in actions folder with together, it can’t be found.