i have a mac and trying create a new excel sheet it will not allow me to write on it

If Excel on Mac will not let anything be typed in a new workbook or an existing worksheet, the supported fixes in the available guidance are:

1. Check whether Office is activated. In a Microsoft 365 app, open the app menu and check About to confirm it shows Activated.
2. Sign out of Office, restart the Mac, and sign back in with the account that owns the Microsoft 365 subscription or Office license.
3. Refresh or remove and re-add the Office license if activation looks wrong. This issue can happen when Office is in reduced-functionality mode, where files may open but editing and saving are blocked.
4. Test in a new Mac user account:
   • Apple menu > System Preferences or System Settings
   • Accounts or Users & Groups
   • Select + to create a temporary test account
   • Sign in to that account and test Excel If Excel works there, the problem is likely limited to the original Mac profile.
5. If the problem continues, completely uninstall and reinstall Office on the Mac.

Also check whether the workbook or worksheet is protected or read-only:

• A protected worksheet can prevent changing cells.
• A workbook opened as read-only can block editing until read-only is cleared.

To clear read-only status in Excel for Mac:

• Open File > Always Open Read-Only and remove the check mark if it is enabled.

If the sheet is protected, worksheet protection must be removed before cells can be edited.

References:

• Set or clear read-only status in Excel for Mac
• Protect a worksheet in Mac
• "Microsoft Excel has encountered a problem and needs to close" when starting Excel for Mac
• Word, Excell won't save documents - Microsoft Q&A
• I have a new macbook and i can not write in excel with my new computer, why? - Microsoft Q&A
• I just installed Microsoft 365 Personal but cannot write or save - Microsoft Q&A