How to mention people in Google Sheet is very easy.
You only need to open your excel file in Google Drive.
This file will be opened with Google Sheet.
After you open it, you can share this file with people who have Gmail or Google Mail.

These people can open and even edit them if you give them edit access.
This method is very effective for managing files that are used together in an organization.
Or commonly called collaboration files.

In this collaboration file you can mention someone, when there is something that needs to be fixed or corrected in the file.
Here’s how: