What you did was help a loser infect Excel with an unwanted macro. Never, never, ever enable macros on a Word or Excel document you don't know the origin of.
Every Excel file you create or open from this point on will possibly have this macro attached to it. These are virtually all Windows malware macros that can't do any harm to a Mac, but you may now a carrier.
Close Excel. Go to this folder in your user account:
/Users/your_account/Library/Group Containers/UBF8T346G9.Office/User Content/
Open these two subfolders:
Chart Templates
Templates
Delete any files with an Excel icon. A template for Excel is typically named Book1.xltx. The number 1 will increment. But it will probably be whatever the crook named it. This assuming Excel automatically saved the template after opening the infected file.
Normal.dotm is Word's template. You don't need to remove that.
If you've opened and resaved any of your own Excel documents, or created new ones since opening the garbage file in the email, open those. If they ask to load a macro, deny it. Open a new, blank document. Copy/paste the data from the infected document into the blank one. Save that and then close and throw the old one away.