Generally, a keyring is a secure password store, that is encrypted with a master password.
Once you input the master password, the keyring gets decrypted and all the passwords inside it are available to the application accessing the keyring.
On Gnome/Ubuntu the
seahorse application can be used to look at the keyring and the master password is the same with your user's password so you don't get asked about it anymore.
Most likely your system's keyring password doesn't match your user's password, or the integration is somehow broken.
You can try to cancel it and see if you still have access to your saved website passwords. Most likely you will be asked for the master password again, as soon as you attempt to use a saved password.