expression, ichidan verb
turn on the light; light a lamp
Expression meaning to light or turn on a light source. 灯 refers to a lamp or light, and 点ける means to ignite or switch on.
暗くなったので、灯を点けた。
It got dark, so I turned on the light.
部屋に入るときは、まず灯を点けてください。
When you enter the room, please turn on the light first.