The proximity sensor. The other, as stated, is an ambient light sensor. One is the proximitity sensor, which allows the screen to go dark when you put the phone to your head, and the other is the light sensor, which allows for using the Auto-brightness on the phone.
Thanks for being with Samsung and for sharing your query. We would like to inform you that it is the proximity sensor beside the front camera. Proximity sensor is used to turn off the touch screen, while making a call when phone positioned close to the ear.
Be sure to hit ♡ when you find an answer that works for you. For Further assistance, you can get in touch with us via Live Chat option by following- http://livechat.support.samsung.com/Customer_new/IN. You can also connect us via Samsung Members web community by following mentioned url-https://community.samsungmembers.com/en_IN#/
