Literature has been using asterisks, daggers, double daggers, etc. to denote markups, notes, corrections, whatever for centuries.
This is going to sound condescending and it’s not intended that way, but read a book. Not a fiction, but non-fiction. Biographies that need research, science texts on detailed subjects, psychology with many interpretations, really anything outside of a storybook.
Have fun learning, and this is not a dumb question. You’re on the right track.