To process a data validation in SIMS you need to go to Admin > Data Validation :

With the latest update, we added a feature to validate a single item as well. 

Basically once you press on Validate single item, a list of all your stock cards will open, and you can select a specific Stock code you wish to validate.

During data validation, the system scans the transactions and location movements, fixes any mismatches in the stock quantities and location quantities.