Hello Shun,
Greetings! Thank you for posting in Microsoft Community. We are happy to help you.
In Excel, you can use the @mention feature in comments to mention someone by using the "@" symbol followed by their name or email address.
- Sign in to Microsoft 365 with your work or school account, and go to a document that's saved in a SharePoint library or OneDrive for work or school.
- Add a comment from the context menu or from Review > New Comment.
- Type @ and the first few letters of the person's first or last name, and then pick the name you want (If they don't already have permission to open the document, you'll be asked to provide that).
Here is a support article for your reference:
Use @mention in comments to tag someone for feedback - Microsoft Support
Feel free to let me know if you have further concerns, I'll be glad to help you further.
If my understanding of the scenario is not consistent with yours, feel free to point it out.
Thanks for your time and cooperation! Have a nice day!
Sincerely,
Tina | Microsoft Community Moderator