Demand sensing is a forecasting method. It uses new mathematical algorithms and previous data to forecast accurate future demands.
Demand sensing is different from the other methods because it uses a much broader range of demand signals and different mathematics for better forecasting that considering real-world events such as shifts in market shifts, weather conditions, natural disasters, buying behavior of customers, etc.
I recommend enrolling in this SAP IBP training by Intellipaat to learn SAP IBP.
Also, check out this video on SAP IBP: