After syncing products, a product status that shows a 'Fail' status means that it hasn't synced over successfully - this is typical when bulk syncing large amounts of products at the same time. In most cases, you can simply try to sync the product again and it will work.
If it doesn't, you can check the activity log to see why it failed.
The most common cause for a failed sync is that there is a duplicate SKU in the destination store. You would need to check and update your inventory to ensure that there are no duplicate SKUs that exist.