A Locked item can't be traded or listed yet, but it will be. The Tradable in label counts down to the moment it unlocks, and after that the item trades like any other.
Why are new items locked?
Items from a Blind Box that's still running are temporarily untradable. The item's info says it becomes tradable once the Blind Box ends, and Tradable in shows the exact time left. That keeps early copies off the Marketplace while everyone is still pulling. Some other items that are still sold in the Highrise shop can be on hold for a short time too.
What does "Tradable in" mean?
It's the time left until the item becomes tradable. The countdown belongs to the item, not to you, so every copy of that item unlocks at the same moment no matter when you got it.
How long does it take?
It depends on the item. The label shows the time left, and the unlock date is set when the item is released. There's no way to skip or shorten it, and Support can't unlock an item early.
Can I list it on the Marketplace while it's locked?
No. Items from Blind Boxes that are still running can't be listed. Once the countdown ends you can trade it, list it, or gift it if it's giftable.
Locked vs Account Bound: what's the difference?
Locked: temporary. It ends when the countdown ends.
Account Bound: permanent for that copy. It never becomes tradable.
If your item has no countdown and still can't be traded, it's probably an Account Bound copy. See What does Account Bound mean?
The timer ended but I still can't trade it
Close Highrise fully and reopen it so your inventory refreshes. If it still won't go into a trade, check whether your copy is Account Bound. If neither explains it, contact Support with your username, the item name, and a screenshot of the item.