a small question, Thanks!

It means to keep something in a place, or in such a manner, so as not to draw attention to it. The tem limelight comes from the theater, and in the theater, the main characters or the main action will takeplace in the spotlight, which is bright, and secondary characters or events will have a "limelight" (meaning a soft, green light) shown on them.

The expression is almost always used to mean out of the mainstream.