S: means stage, 1S means a heating stage. Because you have not set the second heating stage, you cannot see 2S or 3S displayed. For example, to set heating for 3 minutes in standby mode, press Start button, the microwave will stop working after 3 minutes, but please set it as follows: Set 3 minutes in standby mode - Press "Microwave" until "60" is displayed (2S will be displayed at this time) - Rotate the knob to select 2 minutes---Press the "Light Wave" key again (3S will be displayed at this time)---Turn the knob to select 1 minute--Press the start button. Next you will see 1S, 3 minutes. The firepower at this stage is the default 100%, which is 800 watts. After 3 minutes, the microwave oven will not stop working, but will enter 2S (2S, 2 minutes will be displayed), that is In the second stage, the firepower of this stage is 60, which is 60% of 800 watts (480 watts). The microwave oven will not stop after 2 minutes, because there is still a third stage of light waves (3S will be displayed at this time, and 3S will be displayed. Light wave symbol like the sun), the microwave oven will stop completely after the light wave has been working for 1 minute. The microwave oven has been working for 6 minutes. During these 6 minutes, it is completed in three stages. That is, 1S, 2S, and 3S. Microwave ovens without this function can only wait for the microwave to stop working after each stage of work, and then reset again, while microwave ovens with this function can complete it all at once. Let me add that there are no microwave ovens on the market that can set the temperature for heating. The reason is that the error is too large and there are many restrictions on use. In fact, the heating temperature of a microwave oven is affected by many factors, such as the initial temperature of the food, weight, food density, food moisture content, etc. Generally speaking, the longer the heating time, the higher the temperature, but the maximum temperature for water is 100 degrees Celsius. Oils and fats are different and can reach up to 190 degrees Celsius, so you cannot use plastic to heat this type of food. Heating for too long can cause food to scorch or even burn.