How to use bumper sensors?

My brother recently gave me this gadget to ease my pain while parking. The rear camera doesn't always help me, so he offered me this alternative, but I don't know what to do with them. How do you use the bumper sensors?

Don't worry, it's nothing complicated, I helped my niece install it. We decided as a family to give her a little gift after her 1st year of university by getting her a car and everything she needs for it. I decided to go to T1A Auto https://www.t1aauto.com/ to do my best for her safety as her uncle and bought bumper sensors to help with rear parking. They mount directly to the bumper, the instructions are very accessible, it took me about 5-7 minutes to install. Now when she parks, a beep helps her feel the dimensions of the car.