It's the plural feminine form of "la luz," which means "the light".
It can be used to refer to:
* Light sources: "Apagaremos las luces" (We will turn off the lights).
* Illumination: "Las luces de la ciudad" (The city lights).
* Stage lights: "Las luces del escenario" (The stage lights).
Let me know if you have any other Spanish phrases you'd like me to translate!