A WMS answers "what" and "where": what's in stock, where it's located, what order needs fulfilling next. It sits above the equipment-level control layer — a WES or WCS — which handles the "how": routing the physical work to specific conveyors, shuttles or pick stations.
For maintenance teams, the WMS matters less directly than the equipment it drives, but WMS-reported anomalies — a pick station idling with no explanation, orders backing up at one zone — are often the first visible symptom of a maintenance issue on the automation feeding it.