The Advanced Sensor is an upgraded version of the Simple Sensor.
It can detect how MANY matches exist in its target area. By default, this is set to > 0, meaning if there is 1 or more matches in an area, it emits a redstone signal.
You can toggle the greater-than button to less-than or equals to, and then use the number button to the right to increase this.
Example use cases include, sensing if there are less than 10 adult cows, and then emitting a signal to enable a clicker to feed them.
The filter options work the same as with the simple sensor, and you can right click the filter slots to control blockstate detection.