Dreams about boys....wow. Who would ever expect a teenage girl to dream about boys?
As zygote said, it's called puberty............but don't expect it to stop when puberty ends. Women dream about men. It's natural.
To dream that you are flirting or that someone is flirting with you represents your need for intimacy and affection. You may be about to enter into a serious commitment or relationship in the near future.
Just enjoy your dreams...