What do "stocks to watch out" represent?

The home page stocks to watch section is meant to help you have a quick overview on recent level of stocks, considering "active" SKUs (SKUs that have been sold recently).

This section represents the ~20 lowest levels of stock from SKUs sold during this week.
Ex: an order has been sent with 5 units of product A. Product A now has an available level of stock of 10, which is one of the lowest levels. This will become a stock to watch out.

Of course, you are able to have the whole details regarding your stocks on your Inventory page.