noun
pilot lamp; indicator light
A small light on a device that shows whether it is powered on or in a certain state.
電源を入れると、パイロットランプが緑色に点灯します。
When you turn on the power, the pilot lamp lights up green.
Variant with interpunct, sometimes used for clarity.
インジケーター is a broader term for any indicator or gauge, while パイロットランプ specifically refers to a small light indicating operational status.
Loanword from English 'pilot lamp'.