Sensors are hardware components that can provide your computer with information about your computer's location, surroundings, and more. Programs on your computer can access information from sensors, and then store or use it to help you with everyday tasks or to improve your computer experience.
There are two types of sensors:
Sensors that are built in to your computer
Sensors that are connected to your computer by a wired or wireless connection
Some examples of sensors include a location sensor, such as a GPS receiver, that can detect your computer's current location. A program could then use that location to provide you with information about nearby restaurants or driving directions to your next destination. A light sensor installed on your computer could detect the light in your surroundings, and then adjust the screen brightness to match it.
For more information about how sensors may affect your privacy, see How does a sensor affect my privacy?