By sharing an Excel file, you are giving other users access to the same document and allow them to make edits simultaneously, which saves you the trouble of keeping track of multiple versions.

Why does my Excel file show as shared?

Display the Review tab of the ribbon. Click the Share Workbook tool, in the Changes group. Excel displays the Share Workbook dialog box. Clear the Allow Changes check box.

How do I get Excel out of shared mode?

On the Tools menu, click Share Workbook, and then click the Editing tab. Click to select the Allow changes by more than one user at the same time check box, and then click OK. Save the workbook when you are prompted.