You can use the extension window to find a certain password you might be looking for.

Go to the Passwords section to start browsing for passwords.

When you find the one you want, click on its name and you'll be redirected to the site with the user credentials pre-populated in the username and password fields.

Alternatively, you can also open a password from within the extension window to copy the credentials manually, if needed. 

To open a password, go to the Passwords section, but instead of clicking the name of the password you want, click the cog icon.

This takes you to the password in the extension window.