Firstly, how do you not know what Microsoft Excel is? Secondly, she's the one who is using it and is the focus of the memes she is talking about.. and she still doesn't just look it up.
Unless you are in her industry, there are probably tons of things she knows about you and I don't - like good brands of music sheets, mixing desks or microphones.
Excel is known, by a certain selection of office workers.
For a great many folks, the only time they may have encountered spreadsheet software at all was in a school computer literacy class, and even then...
By not being in a office-work career field.
Good argument
She signed a record deal at age 14, back at a time when knowing how to power on a computer was seen as a specialized office skill.
> she's the one who is using it
She isn't a director, and likely had no role in preparing props.