You can create a low stock alert for your store/warehouse.
By setting a threshold, it will apply to all your products.
When the 'stock on hand' falls below the threshold, an email will be sent to the email specified.
1. go to Configuration
2. under 'low stock threshold', input threshold value
3. under 'alert email', input email that should be alerted
4. choose 'alert time'
5. click 'Submit'
The screen at step 4 looks like the following
On top of having an email alert, there is an alert in product list view
By clicking the alert, you will see which product is under stock.