If you are trying to import an old wallet, the GUI wallet will ask you to set a new password for that wallet. If you never set a password using the GUI wallet before, then it shouldn't ask you to put in a password, unless it is asking you to set a new password for the new wallet you are about to create using your private key/seed or one it generated for you.

You can tell it is asking for a new password when it asks you to set the password twice. (To ensure you typed it correctly) Any time after that, you will only need to enter the password once.

Keep in mind; this password is just so only you can access your wallet using the GUI. Your seed/private key is not tied to any password you set. So even if you forget your password you still have access to your funds as long as you have your seed/private key.