In indirect speech, the speaker's words are reported by another person. In this case, the original direct speech is "Remember to switch off all the lights," and when it is reported indirectly, it becomes "She reminded me to switch off all the lights."

The key transformation here is changing the imperative "Remember" to "She reminded" and retaining the content of the instruction. The verb "reminded" is used to convey the idea that the speaker is reminding someone (in this case, "me") about the action to switch off all the lights.