Real-time means a change in one place shows up elsewhere almost immediately. A sale at a till updates the stock count, or a driver marking a delivery complete updates the customer's tracking page, within moments rather than at the end of the day.
It is valuable where decisions depend on current facts: reallocating a van, spotting a stock-out, or answering a customer on the phone. Real-time is a matter of degree, and not everything needs it. Daily summaries are perfectly adequate for some figures, and choosing where speed matters keeps systems simpler and more reliable.