...a light switch.是什么意思？

...a light switch.

电灯开关

light

n. 光，发光体，电灯，点火器；adj. 轻的，明亮的，浅色的，少量的；v. 点燃，照亮，用光指引；adv. 轻地，轻装地；

例句
...the light of the sunset's afterglow.
落日的余晖

switch

n. 开关，转换，转换器，软鞭子，[信]接线台；vt.& vi. 转变，改变，转换，关闭电流，鞭打；vt. 转换，挥动（棍棒、鞭子等），迅速转动，鞭打；vi. 交换，调换；

例句
What he wants is a switch to a market economy in a way which does not reduce people's standard of living. To many this sounds like wanting to have his cake and eat it.
他想要转型为市场经济,同时又不降低人们的生活水平。在许多人看来,这是想要鱼与熊掌兼得。