Incorrect Name Syntax

Good Morning,

I am new to Excel (watched one video in Training Session). Doing homework by using Excel Inventory Template. I have been copying and pasting to add to the number of cells in the Worksheet. I have 3 open worksheets. (They are all frozen)

I attempted to highlight an entire column to remove the cell's contents and got an error above that cell column '@[Quantity in stock]]. After that,  every time i tried to write in a cell or highlight, I got the dancing broken lines and in the formula bar the message '=[@[Unit p+H87:H111rice]]*[@[Quantity in stock]]' and the error message ' The syntax of this name isn't correct. Verify that the name:

-Starts with a letter or underscore (_)

-Doesn't include a space or character that isn't allowed

-Doesn't conflict with an existing name in the workbook.

I had nothing to do with the creation of the formulas. Microsoft Support asked me to cross reference the formulas with the original document but I don't have any idea how to. She then forwarded me here.

I have over a hundred rows of information inputted in the columns and sincerely hope my situation can be remedied to save the day.

Thank You