First, Majel Barrett had several Star Trek credits: the TOS Enterprise computer, TOS Nurse Chapel, Number One in The Cage, Deanna Troi's mother in TNG (never can spell the name of that character correctly) and the ship's computer again in TNG.

Second, Number One is how the Executive Officer, or First Officer, of a ship is addressed, especially while on duty, whether it is on a real-life naval military vessel or a fictional Starfleet ship.

Whoever wrote this article needs to do a bit of research now and again.