To password protect an Excel file, you can use the built-in encryption feature. Here's how to do it in Excel:
1. Open the Excel file you want to password protect.
2. Click on the "File" tab in the ribbon to access the Backstage view.
3. In the Backstage view, click on "Info" in the menu on the left.
4. On the right side of the Info pane, you'll see options related to protecting your workbook. Click on "Protect Workbook" and then select "Encrypt with Password" from the dropdown menu.
5. A dialog box will appear prompting you to enter a password. Enter the password you want to use to protect the file and then click "OK."
6. Confirm the password by entering it again in the confirmation dialog box and then click "OK" again.
7. Save the file to apply the password protection.
Now, whenever someone tries to open the Excel file, they will be prompted to enter the password you set. Make sure to remember the password, as there is no way to recover it if you forget it. Additionally, it's a good practice to store the password in a secure location or with a trusted password manager.