What is the use of a Photocell Sensor in an LED Pole Lights?
Automatic power on / off.
To prevent the LEDs from coming on as long as there is sufficient ambient light. In other words, the LEDs won't come on until it's actually dark out.
It's used to measure the ambient light. This measurement is then used to increase or decrease the luminosity of the LEDs. For example, at night the LEDs don't need to be bright, but during the day the ambient light will drown out the LEDs so they need to be brighter.