How does this battery light work?

Equipped with a rotatable and sensitive motion sensor, it works only in dark environments, the light will turn on If people or animals' motion are detected, then if no motion is detected, the light will turn off automatically after 20s.

Why does this battery powered spotlight occasionally light up during the day or indoors? Any problem?

This is not a fault, the floodlight has a sensitive sensitivity that allows it to recognise night in relatively dim indoor or daylight conditions and trigger the motion sensor to switch the light on.

Is there on off switch ?

Yes, it is on the back side of the middle light panel.

Is the battery floodlight suitable for outdoor installation?

Yes, the security light has a splash protection rating of IP65, so it can be installed outdoors without any problems, but for more durability and longevity it can be mounted under something sheltered.

Does this security lights outdoor motion sensor include batteries? What type of batteries do I need to use?

Batteries are not included in the package, it requires 3 alkaline batteries.