Adding a password to a zip file on a Mac is a simple but essential step to secure your sensitive data. Here's how you can easily add a password to your zip files:

1. Locate the zip file you want to password protect.
2. Right-click on the zip file and select 'Compress'.
3. After the zipped file is created, select it and click 'File' in the top menu bar.
4. From the dropdown menu, choose 'Encrypt [filename]'.
5. You will be prompted to enter a password. Enter a strong password and verify it.
6. Your zip file is now securely password protected!

It's important to use a strong and unique password to enhance the security of your zip file. Remember to securely store your password to prevent unauthorized access.