With the Sirens, mythology has created a physical personification of the danger of falling for a beautiful woman. As any man knows, beautiful women can be dangerous. In Greek mythology, some beautiful women can be straight up deadly.
The Sirens of Greek mythology began specifically as a group of creatures who looked like beautiful women, but were really man-eating beasts. They sat on the shore and sang with voices so seductive and compelling that anyone who heard their songs became absolutely mesmerized with them. So mesmerized, in fact, that they became obsessed with reaching the shore to get closer to the sound. And then the Sirens would eat them.
The term "siren" is used to describe something that is simultaneously dangerous and compelling. In later myths and legends, any creature that lured a man in only to cause harm might be considered "a siren".
When I say "a man", this is usually because in myths the siren was usually a female who lured a man in with their beauty. In modern stories, one might consider the male vampire to be a creature who uses its seductive abilities to lure in women in order to drink their blood.