That means you will have to send a trade offer containing all your in-game item(s) to any of your other accounts, friends or any trusted account in order to keep your in-game item(s). Once the account is successfully secured, you will be able to send all your in-game item(s) to this account. Keep in mind that all the mentioned actions needs to be done in 24 hours from now. We're truly sorry for such a bad experience, but we have to do that in order to prevent malicious users.