This is a general term for “placeholder.”
Here’s how we got to this definition, from Wikipedia:
In computer user interfaces, a cursor is an indicator used to show the current position for user interaction
Cursor is Latin for “runner.” A cursor is a name given to the transparent slide engraved with a hairline used to mark a point on a slide rule. The term was then transferred to computers through analogy.
So, a “cursor” is that clear plastic piece that slides along the length of a slide rule. I don’t know how a slide rule works, but I understand that was used as a placeholder.