The keychain in OSX/MacOS is a place for storing passwords for other systems, certificates etc

Windows has a similar system for certificates, not sure it has the same for passwords ?

To access the stored passwords:

Hit cmd-space, to bring up Spotlight search.

Type "Keychain Access", hit return to open the Keychain Access app.

In the top left "Keychains" panel, select "login".

In the bottom left "Category" panel, select "Passwords".

Find the password you want on the right hand panel, double click on it to open it.

Check the "Show password" check box to see the password.

At some point in the process you'll get a popup asking for your login password.