What's "turn on" mean?

Native speaker’s answer
Rebecca
To be "turned on" [by something] means to be physically attracted to something. For example, some people are turned on by particular physical features or clothing styles. In this case, the lyrics are expressing the singer's physical attraction to someone (he is making a pun here, as light switches are "turned on"). Ex: He was turned on by women with red hair. Ex: I get turned on by big biceps.