Product Availability Slots general settings
How to setup product availability slots provides you details on how to configure the basic settings of plugin.
Unavailability Text
The option allows you to add product description when it is unavailable.
Availability Text
The option allows you to add product description when it is available.
Set Day Label: Choose the label from drop-down such as D, Day, or Days.
Set Hour Label: Choose the label from drop-down such as H, hour, or hours.
Set Minute Label: Choose the label from drop-down such as M, minute, or minutes.
Set Second Label: Choose the label from drop-down such as, S, second, or seconds.

How To show availability or unavailability slot
Add a new product under the products tab. Create new product select simple or variable products from the drop-down. Click on availability slot tab. You can see seven days where you can enable or disable slot. You can add a time slot for different days for product availability.

Display product availability at the simple product page
The product availability slot is showing in the screenshot that the product will be available after 6 and 9 hours. However, you can also add the custom text such as, the product is available for a short time.

Display product availability at the shop page
The product availability slot shows in the screenshot that the product will be available after different hours on the shop page. However, you can also add the custom text such as, the product is available for a short time.

The above procedure provides you proper details about how to setup product availability slots.