You and your colleagues can open and work on the same Excel workbook. This is called co-authoring. When you co-author, you can see each other's changes quickly — in a matter of seconds. And with certain versions of Excel, you'll see other people's selections in different colors. If you're using a version of Excel that supports co-authoring, you select Share in the upper-right corner, type email addresses, and then choose a cloud location. But if you need more details, like which versions are supported and where the file can be stored, this article will walk you through the process.
Source: Microsoft