How to rotate hundreds of objects without key framing each of them?

Thank you so much for the explanation. After checking the screenshot, I realized that I really need to start learning about blueprints from the fundamentals (and I’m doing it).

I have a question about “For Loop” though.
As for experiment, I wanted to make a light flicker for 15 times using For Loop node. Here’s what I did:

…and it didn’t work. Could you tell me what I should change?