This tool is for recalculating the calculate fields of ATUM: Stock on hold, Reserved Stock, Backorders, Sold Today, Customer Returns, Lost in post, calculated stock...
The average performance is that when a client buys a product, for example, all these values of the products are calculated. However, in order to reduce the loading time, they are not calculated immediately, but it is added the order of the calculation to be executed later on the server, in background
However, Wordpress can't do this but its own, and it does it while the user is connected on the website. But if the users buys and he/she close the page quickly or if the internet stops working... there is a probability that the product properties are not updated.
This can lead us to cases in which we go to SC to see what we have sold and the values we see do not correspond with the orders we have attended.
In such cases, if we run that Tool, it will recalculate everything
Hope this helps,