Siren has two main meanings:

1. A device that makes a loud, wailing sound to warn people of danger or signal an emergency. When you hear the siren of a fire truck or ambulance, that piercing noise tells everyone to clear the way because help is rushing somewhere fast. Air raid sirens warned of incoming attacks during wartime, and tornado sirens alert communities when dangerous storms approach. The sound is deliberately attention-grabbing and hard to ignore.
2. In Greek mythology, sirens were dangerous creatures who sang so beautifully that sailors couldn't resist steering toward them, causing their ships to crash on rocky shores. The hero Odysseus had his crew plug their ears with wax so they could sail past the sirens safely. Today, when something is described as a siren call or siren song, it means a tempting attraction that might lead you into trouble, like the siren call of video games when you should be doing homework.

Both meanings share the idea of a powerful sound that demands attention and can't easily be resisted or ignored.