Click the File tab in the top left corner and select Account from the menu on the left:
Under Product Information, you'll find your Office product name and, in some cases, the full version number.
In the About Excel section, you will find the version number, which includes version, build number, and the type of installation such as Click-to-run or Windows Store.
To find out the bit version, click About Excel in the Product Information section. When the dialog box opens, you'll see the full version number and bit version (32- or 64-bit) of your Office at the top: