iCloud Passwords allows you to use the same strong Safari passwords you create on your Apple device, with Chrome on Windows. The new extension is now available in the Chrome Web Store. The passwords created in Chrome for Windows will sync back to iCloud so they'll be available on Apple devices as well. iCloud Passwords also saves any new passwords you create in Chrome to your iCloud Keychain so that it is also available on your Apple devices.
Keychain is the password management system in macOS. It was introduced with Mac OS 8.6, and has been included in all subsequent versions of the operating system, now known as macOS. A Keychain can contain various types of data: passwords, private keys, certificates, and secure notes. With iCloud Keychain, you can keep your passwords and other secure information updated across your devices.