If you see an item marked "Suspended with Substitute" in the Hailo app, that means that the particular item is not available, but the supplier has a substitute on hand. You can order the substitute item through Hailo.
You will see the substitute item listed in your Hailo app, underneath the original item. On your order list, update the quantity of the substitute item (as normal) to add it to your cart.
More info on Special Order Status' can be found here.